If your Soundblaster PCI is working correctly in Windows, then it'll hopefully have created a folder C:\SBPCI, which contains all the DOS drivers you need. If not, you can find them in the Vogons drivers library.
In there, you should find:
SBLEGACY.EXE - run this, and it'll tell you whether the correct hardware is present and functional.
SBCFG.EXE - this one will tell you which ports and channels the various sound devices are using, which is useful to know when setting up DOS games.
SBINIT.COM - this needs to be run after every boot to enable sound in DOS. You can simply add the line C:\SBPCI\SBINIT.COM to the end of your autoexec.bat file to make this happen automatically.
SBTEST.EXE - run this to do a quick diagnostic test, if everything's working you'll hear some sample sounds.
SBMIXER.EXE - this allows you to set the sound levels for digital audio and music
The DOS version of Simon the Sorcerer doesn't support General MIDI music. You can either use Soundblaster/Adlib music, which the SB PCI emulates rather poorly, or Roland MT-32 music, which for your setup will sound similar to General MIDI.
If you want to put the SB PCI in MT-32 mode you can type MT32 /ON at the DOS prompt. If you don't do this, it'll still play, but you'll hear all the wrong instruments. Note that this command will only work for games which just use the preset MT-32 sounds- any games which try to send custom patches (expecting a real MT-32) will sound very wrong!
MT-32 Editor- a timbre editor and patch librarian for Roland MT-32 compatible devices: https://github.com/sfryers/MT32Editor