In the end, it's really just something like MIDI music with custom instrument samples, I understand.

Offhand, everyone seems to like FL Studio (formerly FruityLoops) for that sort of thing. That's expensive, but there's a demo available, I think.

Otherwise, ModPlug Tracker springs to mind. Seems they call it "OpenMPT" now:
http://en.wikipedia.org/wiki/OpenMPT
http://www.modplug.com/

Buy an Amiga. 😜

If you've never made music before then using a tracker is a bad place to start because you have to supply your own sound samples. :P

I recommend starting with a MIDI-capable program since with one of those, you only have to worry about the music itself and not the sound samples too.

Don't expect to figure it out overnight though. It took me SEVEN years of tracking to get my music making skills up to a level I felt was good enough to have other people listen to. I had also been doing MIDI music for half a year prior to starting tracking and had been playing musical instruments since the age of 4. (I had one of these things and in fact, STILL have mine: http://m.matrixsynth.com/2010/12/vtech-music-major.html )

My first tracking was done in Scream Tracker, though I quickly moved up to Impulse Tracker, and I haven't used anything else since... primarily because I can run my IT files directly in any games I make, which helps to save on space since IT files are tiny compared to MP3s and OGGs! ;)

Trackers are really nice composers, but may be overwhelming at first, especially for beginners - due to the sheer number of numbers, icons, tracks, and a multitude of buttons.

My first experience with trackers is the Dos' Tetra Music Compositor. Was previously bundled with Sound Blaster Pro. (But also was available separately at that time.)

The basic idea is like this - you take the required sounds from a pool of samples and put them together.

Depending on the tracker, there will be numerous "tracks".

Each track consists of 60 (or any other modifiable numbers) of "placeholders". You have to load a sample from the pool, and place it on the place holder. Usually once the samples are loaded, the tracker will assign the keyboard's row of keys as the note inputs.

For example, A key may stand for the C1 note, S key for C2 note, D key for C3, etc.

Usually, we place, for example, the drum sound in one track - so when a drum sample is loaded and the notes entered into the track, and when we run the track, each drum sound will be made to play, when the entered note gets "sensed" or "touched" by the highlighted, static "counter" or "trigger" if you prefer.

Then we place the sample of, say, piano in another track, keeping in mind each key represents a note, on another track.

So now, when we let the track "run", we hear the drum sounds and the piano playing. Add more samples like bass, synth, cymbals, etc, and you have a studio running!

Now, each sample is nothing but a recorded sound. Like the drum sound. The Tetra Compositor I mentioned earlier supports live recording via a mic, and the program will convert to the sample format and save it into the pool of samples. The program will automatically shift the notes up or down, when a key is pressed. For example, a single recorded piano note, say C3, can be shifted to C4 or C1, to D or E note or B or A note.

The sample can be anything recorded via a mic. Like piano, drum, a coin dropping, or even your own voice shouting the trademark Michael Jackson's "aaoowww".

And most trackers will allow you to "extract" the samples from the song. So, if you like a certain sound or instrument in a song, you can extract it and save it to your pool and re-use them.

There are also many freely available samples to download.

But keep in mind, that most songs have copyrighted sound samples or have royalties attached. And some others don't have. Anyway, nothing will stop you from extracting these samples from the song or mod, and that too, it only matters if you're gonna sell your song using the copyrighted or royalty attached sample.

If you like listening to music, you'll be hooked to the trackers. Until you begin, you'll never know. 😉

Here is a place to begin - http://www.madtracker.org/about.php (Madtracker is a Windows compatible tracker, and works just like how the Dos trackers (or Amiga trackers) those days. The basic concept remains the same.

You can also download Dos' Impulse Tracker or Scream Tracker or Fast Tracker for use with Dosbox.

I use an older 2002 build of Modplug Tracker as I hate how OpenMPT rearranges things and feature creeps.

Be aware that Modplug has a stigma because it introduced some Modplug-exclusive hacks to the .it format to allow VST filters, bringing accusations of heresy from the tracker communitiees. I'd not rely on those, and I stick to making .mod files anyway that are just 8trk and pan abusing.

Malik just laid down the basics very nicely, but this is a subject where I have to butt in anyway...

I'm a lot like Gemini here - started with Scream Tracker (back when it was 2.x... pure 80x25 textmode tracking ftw), then moved on to Impulse Tracker (basically a much-improved Scream Tracker with more features, and the last king of the DOS tracking scene). I play a number of instruments and have done stuff from game music to home recording over the years, yet to this day, I still have no idea how to really use MIDI. When I need something programmed, it's always a tracker.

Modern trackers are very different beasts from "classic" trackers... these days you can use stereo samples of any bitrate you want, have "virtual tracks", plug-ins, modules, even VST effects on channels, and you get trackers like Renoise which are basically mini-DAWs in themselves. The "classic" tracker sound is 4 to 8 channels and 8-bit samples, though in the latter days of DOS this was already extending to 64 channels and 16-bit.

Trackers don't even have to be based on samples, by the way. You can find OPLx trackers, SID trackers, even a PC-speaker tracker (Monotone), and so on. ;)

The "classic" tracker sound is of course sample-based - but what defines a "tracker" is really the interface:
- You arrange notes sequentially in channels - visually from top to bottom
- Channels are mixed together to form a "pattern" - a group of channels played simultaneously and viewed side-by-side
- Arrange these patterns into an "order list", and you have your tune.

The specifics vary... but I'd say that around the mid-'90s, two distinct "schools" of tracker interfaces emerged: "Scream Tracker style" and "FastTracker 2 style". The differences aren't major, especially if you're new to tracking, but when you get used to one you'll hate the other. ;) Most trackers after that, even to this day, are still descended from one of the two.

Since you're new to tracking and also to composing music in general, you will probably want a very basic, "classic"-style tracker, maybe running on an emulator (or just using a modern clone). When I started tracking I did have some experience and theoretical knowledge of music, so I can't really have more helpful advice than that... (though I'd bet that at least a few of the big name "scene" composers were self-taught)