Well, if you're certain that you know what notes you can find on a guitar, where you can find them and how to read tablature, you can move on to lesson two. I am sure you have heard of 'chords' before. Lets' begin with the major chords.
Every note has a chord, so there are seven major chords to learn.
To play an A chord, place your fingers on the D, G and B string on the second fret. Then, play the chord, but don't forget not to play the first string. Now take a look at these chords an try to play them one by one. Take your time, because this isn't easy, but it is necessary to know what you are doing. Some of the above chords demand some stretching of fingers here and there, but with a little practise, you'll do alright.