Practice, practice, practice!
The best way to learn, I've found, is to take a few lessons to start. Then get some tabulature on some of your favorite songs, learn them, and play along with them on your stereo.
Get yourself a good amp, tuner, cords, and alot of picks.
Tab shows you where to put your fingers and which strings to pluck. Its much easier to read than to read notes. Tab is split into six lines that are horizontal.
Top line = E (The thinnest string)
Next line from the top = B
Next = G
Next = D
Next = A
Next = E (The fattest string)
so....
------------------ E (High E, if you are playing right handed, its closest to the floor)
------------------ B
------------------ G
------------------ D
------------------ A
------------------ E (Low E, if playing right handed, its the one closest to you)
Now if your guitar is in tune, and you put one finger on low E right below the 5th fret, and one finger on A and D right below the 7th fret, and play those three strings, it will make a chord. Shown on tab, it looks like this....
--------------------
--------------------
--------------------
7-------------------
7-------------------
5-------------------
Its easy.