First of all:
Welcome to OnlineDj, we're happy to see you! You can learn alot here, believe me!
Now, About your question:
Well... Here's the thing:
1) You can compose music like I do:
Fairly cheap on a computer, (I have an OLD synth too).
I use so-called software synths to make the sounds. And sometimes my keyboard to control notes and volumes.
2) Or:
On alot of expensive hardware, with a sequencer, a synth, and maybe a drummachine + alot of effects.
If you aren't loaded, I suggest you don't ask any more questions about this part:
3) Or:
Like ManoOne is doing.
Using a computer to control a hardware synthesiser (In his case: Acces - Virus B)
It all depends on how many money you wan't to spend and on how keen you are on getting into the music buissness.
We'll try to help you with anything you ask, but your question for now is very broad. It actually covers every aspect of the buissness.
Search your soul and you'll find the answer to what you want. (hehe
) Then we can guide you to other threads or simply help you rigth here!