What are the main topics about music theory? I've played bass guitar for almost two years, but I havent studied a lot of theory. I want to learn more about music theory, but I don't know where to start. Please give se some advices or some links where I can start.:help:

I found the "Bass Guitar for Dummies" book excellent for teaching basic theory.

A website I also found good was www.studybass.com

While you can learn a fair amount of theory on your own, a good teacher would also be a good idea in helping you to put it to use. This combination of book, net, and teacher has worked for me.

The best place to start, in my opinion is to find a good tutor. Make sure you find someone who is going to teach you about actual theory and theoretical concepts starting with the major scale and diatonic theory, including modes and how they relate, triads, extended chords and so on. Don't settle for someone who just wants to show you a major and minor pentatonic and then teach you a bunch of songs from a cd.

Feareol has some suggestions for getting started and there are many links on basic harmony and theory and as related to bass. I would say just focus on the major scale, how it is constructed, intervals, harmonized major scale and how to chord progressions using the roman numberal system. Learn how chords are constructed and arpeggios. There are basic ear training site on the net work on hearing intervals of the major scale while learning the scales. Learn all the theory as related to the fretboard. Take songs you already know and analyze the progressions. Take bass line you know and figurre out which are chord tone and what other notes are being used.

In other words learn the major scale inside out, every aspect of the major scale, its intervals, harmonry, how to recoginze intervals when you hear them, how all of this looks and plays on the bass. Once you know the major scale to that degree you will have a firm foundation and can move on to other scales and modes. You will find if you take the time to learn everything about major all other scales and modes will come very easily and very fast because you have point of reference to compare/relate to.