ive been learning theory but i dont know how to find the root, for example im guessing anna molly by incubus is depending on the key either in c aeolian or f dorian

The root note tends to mean the root of the chord, not the key.

So if it's a C chord, then the root is a C, etc.

If you can find the root of the chord that's being played, the rest should be a lot easier, as you know the notes will be in the chord or at least something that sounds good with that chord.

I haven't even gotten past the first step, so I can't really help you beyond that.

If you wanna know the root, look at what the bass player is playing on the downbeat... Works 98% of the time.

If you're looking for the key, try to figure out what the very first or very last note of a song is... that often works.

ive been learning theory but i dont know how to find the root, for example im guessing anna molly by incubus is depending on the key either in c aeolian or f dorian

Either way you're talking the parent key of Eb major. Put your bass down and sing the root movements. Get the sound of the progression in your head firmly. Then you can pickup your bass sing the roots and try your different scales/modes and see what key it is in. Write down the chord progression and look at it. Music want to resolve listen to the tune and follow the progression on paper. When the song feels like it gone back home what chord is it on.

Listen and sing first get the song in your head, then use your theory if still stuck.

I love theory and glad to see people wanting to learn and use it, but I feel a lot times they are putting the cart before the horse. Use your ear first, then if you need help look to theory to give you clues. Then use theory to see if what you came up with makes sense. Listen first.