Play either the G major scale or the G major pentatonic scale (which is just like the major scale with fewer notes). Have a few goes through then try it at your own speed with the G major backing track (which starts after one bar rest and a count-in).

UKULELE:  C major   G major   D major   F major   C blues   G blues   D blues   F blues

UBASS:  C major    G major    D major   F major   C blues   G blues   D blues   F blues