type "dir"

Okee, and then?

If you can't figure it out yourself from there, post a screenshot of what you get after typing "dir" and a solution should present itself.

So, what should I do now?

Change directory (cd) to SUPAPLEX. Is tdcga.com or tdcga.bat located in that directory?

I'm not sure what you mean by that..
The first thing you said worked.

...

Oh dear. Is this the guide you're following?
http://www.dosbox.com/wiki/index.php?title=Ba … ation_of_DosBox

For starts, that is not Wikipedia. That is the DOSBox Wiki. (There are many, many websites out there that use the same software as Wikipedia.)

Secondly, that is an example for running a specific game, Test Drive. You are not trying to run Test Drive, so of course if you follow the instructions exactly, it won't work! Please see the 60 Seconds Guide to DOSBox for more generalized instructions.

Thanks for telling me I'm doing it wrong.
I found my way, so I can play the game now!
Many many thanks!!!
[/i]

If you're not versed on the usage of MS-DOS, maybe yopu'll be better off using a frontend to launch your DOS programs. With DBGL or D-Fend Reloaded all you have to do is point towards the excutable (that would be SUPAPLEX.EXE here) and be done, because most programs will work with default settings.