[HELP!] Oriented Surface Integrals

I'm stuck with a oriented surface integrals question...

I don't know how and where to begin...

The question's asking to evaluate the surface integral for the given vector field and the oriented surface S. In other words, find the flux of across S. For closed surfaces, use the positive (outward) orientation.

__Q29. Pg 1092__ (sorry, this is just for my own reference to refer on later on)

, S is the boundary of the solid half-cylinder ,

How should I think of this question and where to start? Which formula to use? What are the boundaries and how did you find the boundaries?

Please help me~