Learn and play simple chords (e.g. take a-minor on a guitar), and then identify the individual notes that are played by using any fretboard diagram or guitar chord finder app.
Obviously chords are not magic but consist mainly of a root note, a third and a fifth (look up "minor chords" and "major chords" if needed). You can find other occurences of the relevant notes all over the fretboard and make your own chords or at least understand what you are doing.
Example: For example, check out "Drive" from Incubus. What the heck is the guitarist playing at the beginning and how did he ever come up with that? https://www.youtube.com/watch?v=RpwsuhOUAkk
You can check out what he plays here and identify the names of the first notes: http://www.songsterr.com/a/wsa/incubus-drive-tab-s327t0
It's just another way to play e-minor!
The intros to Stairway to heaven, Nothing else matters, Bach https://www.youtube.com/watch?v=f6haO4rO7rk? That's all just chord notes played one by one. Don't hesitate, compose a legendary rock ballad intro TODAY!
I'm writing that because most teachers and students feel that this is too theoretical and complicated, and the classicaly trained musicians I know read their sheet music, but don't usually identify nor instantly recognize the chord that they're in while playing Vivaldi either.
I found it really helpful to understand that all that wonderful music is made of basic bulding blocks that I can understand and play, and it's a nice excercise that you can do while your hands recover from those little beginner muscular cramps or pain in the finger tips cut by steel strings.
Then however switch it all off and just play :-)