How do you compute the volume of a solid formed by revolving the given region about the lines?

the directions are:

compute the volume of the solid formed by revolving the given region about the line

region bounded by y=2x, y=2 and x=0 about (a) the y-axis; (b) x=1

It has to be solved with a definite integral

V=∫A(x)dx,a,b

im not 100% sure how to do this, please help