× = don't play that string, ○ = open string. Numbers next to a diagram give the fret it starts on.
See every C♯m7 note on the neckC♯m7 is one of the seven chords in: A major (iii7), F♯ minor (v7), E major (vi7), C♯ minor (i7), B major (ii7), G♯ minor (iv7).