1: Learn all the major and minor chords in first position (masses of information on how to do that in books and on the web, you only need to read chord boxes which tell you where to put your fingers, no need to learn how to read music on the stave.)
2: If you like Mayer you like blues presumably?, learn to play a major and a minor 12 bar blues, chords first then learn some single lines/licks to use over the top, again, masses of info around on how to do this.
3: Start learning the theory. Learn about the major/minor tonal system, learn to play each chord in a major and minor key and understand their functions (cadences, cycle of fourths/fifths, and so on.)
4: Make things more interesting by using altered voicings, using proper voice leading, chord substitutions, modulations and so on.
This will all take years and years to do well. You might just want to stick with steps one and two and have fun without knowing how it all works (learn some chord shapes, a few 'licks' and use your ears.)
Up to you.