In response to the question about if you need any inherent skill to compose. No. You don't need any sort of musical talent what-so-ever. All you need is the inborn NEED to compose, and you will find some way to work around any lack of a good ear or junk like that. And even if others tell you that "No, you wont write anything good," then take this site off your favorites list and don't visit it anymore, and compose anyway. Composition is for you, and you only. Not the listener, not the critics, not your teachers... you. And if you manage to write something that people lik, well, all the better for them.
Note that this is not to say that you shouldn't ever take someone's advice on what to do to improve your piece. That is advice that, in the long run, is better to take, just because you yourself begin to see new possibilities, and new ways of doing things.
The only way to know if you can compose or not is to start composing. Anything. Write down random notes if you want. Find a music notation program and just put in all eigth notes. Whatever. Just as long as you start getting a feel for what works, what doesn't, and how to go about the whole thing.
good luck.