Hi, Michelle!
I'm sure there are various on-line courses for composition, but you could also see if there is a composition teacher near you - there are often intrumental teachers who also offer composition, if only basic, so it's worth asking around.
What kind of composition were you interested in? Classical music? Song writing? Some people think composition is easier if you play an instrument, especially something like a piano, but I don't think that's necessarily true, if you can your music in your head. And, as with anything, it takes practice, and you can start off with the basics.
Some people find it helps to start with a basic tune, and then add chords to change the feel of the tune. It can also be useful to take a section of a well known tune, and write a variation of it - change the time signature, or change the key from major to minor.
Good luck in finding a teacher or a course that suits you, and I hope you enjoy it
Jen