riff X:
[E--------------------------------------------------
B-----1--------1--------1-----1--------1--------1--
G--------------------------------------------------
D--------3--------3--------------3--------3--------
A--5--------5--------5-----5--------5--------5-----
E--------------------------------------------------
riff Z:
E--------------------------------------------------
B-----0--------0--------0-----0--------0--------0--
G--------------------------------------------------
D--------3--------3--------------3--------3--------
A---5-------5--------5-----5--------5--------5-----
E--------------------------------------------------]
You just play riff X, into riff Z, back to riff X, so on, so forth.