I don't entirely understand what you mean. Do you only use your computers wavetable midi or do you mean you only use soft synths? If you use midi via for example TTS1 or the other synths you can mix and add effects and mix right away. If you don't use soft synths but only the microsoft wavetable, start using soft synths emidiatly

Check out the tutorials in your manual, I think they are pretty good for begginers.