The C Major scale is going to be all the notes without any sharp or flat notes, just the basic note names. C is the third fret on the A string. You play the open D one string away. You play E second fret on the D string. F is the third fret on the D string. Open G. A is the second fret on the G. B is 4th fret, and that brings us back to C, 5th fret. And that's a C major scale on the bass guitar.