2/4 time means you play 2 beats to the bar. Each note = a 1/4 note ("quaver")

Repeat brackets = repeat lines. Note the Volta brackets 1 and 2. So play line 3 in repeat.

Part B of the riff: This is called a "chromatic" scale because it moves one fret at a time.

This is also a chromatic chord sequence, moving down just one fret at a time..........

..... and although the chords are not all similar they are all harmonic equivalents ("7ths")

Here I revert to 2/4 time as Part A of the riff returns.......

Play this line 3 times then go on

Play last line anyway you choose but hold last 2 chords x 2 beats