Note B

B
A string, 2nd fret
25EADG

B: middle finger on the A string, 2nd fret

The fifth F# (pearl dot with the 5): D string, 4th fret – one string higher, two frets further. Root and fifth in turn: that’s the simplest bass line.

B all over the neck

EADG1234567891011127942

E string, 7th fret · A string, 2nd fret · D string, 9th fret · G string, 4th fret

Other notes

B as the root note