We are an accompaniment instrument, which means we accompany the melody by playing notes of the harmonizing chord, one note at a time to the beat of the drummer's kick drum.
To do that we need to know what chord is active in the song. I do this by playing from fake chord sheet music like this; Above All
Are you telling me that all I need to do is dig out all of those old chord box books I have from years ago when I tried to play guitar, and play the matching arpeggios over the guitar chords (puts head in hands), why didn't I ever think of doing that? Why?