We need to know a bit more about what you are currently/ or want to start studying to help you out a bit more on what you should know etc. Getting a theory teacher can really help too, or even just a general instrument teacher helps (although I'm myself self taught in both areas, there has been many times I've come across classically trained kids that didn't know about certain concepts that I even knew about).

 

Definately!

 

I took a music theory class this year at my school, and I've learned so much about tonal harmonies, structures, key and modulations. Even time signatures and voice leading took up big portions. Really yo wont go very far in music if you dont too much about theory.

You can compose without formally knowing music theory, (just look at Lennon & McCartney), since as you learn to play an instrument you pick up many of the rules of music composition just by seeing how different tunes are put together. From this you develop an intuitive knowledge of what works and what doesn't.

 

What understanding even the rudiments of music theory does is explain why you do what you do and why that works. But what it will also do is allow you to see alternative ways of doing it and when (and how) you can break these "rules".

 

To start I sugest you go to a library, borrow any book on Music Theory and skim it - I'm fairly certain that you will find something in there that will click or register with something you do because you've always done it like that and you'll see it in a new light. If you don't, then return the book