To use the tablature to determine chords on higher frets, just pretend like the fret below the first fret you are using is the top of the fingerboard (nut). Then count how many frets there are between that fret and the actual top of the fingerboard. So if the chord you are playing appears as E major in the tablature and you are seven frets above the nut, count up seven half steps from E major. E-F-F#-G-G#-A-Bb-B. You are in B major.