google is your friend.
try reading some books. google will help you find the right ones.
what aspect of audio are you interested in? production, recording, editing or everything? whatever the case, google will help you decide.
google google
seriously though, i did a course for audio engineering and the shit is horribly out of date. get some books on whatever field of audio you would like and study. then look around at some forums like futureproducers.com (to mods- im not trying to get users to switch to this, but the forum is nearly exclusively audio related and might be of help to seb). search the FP forums and you will find many topics of relevance.
for mixing techniques, i suggest you get a book or find some nice indepth tutorials.
you can't learn mixing in a snap (such as from one forum post).
you will need to combine lots of reading with your personal trial and error experiments to get a really good idea of how you can mix and manipulate things to sound good together.
some might tell you that since its audio, your ear is the most valuable learning tool. if it sounds good, it is good.
this is true to a certain extent. however, you will want to mix some theory in.
good luck in your journey, and im sure some others here will add to this.
