I'm just going to assume that you're being asked to graph the surfaces defined by those equations; it sounds like your book might be a little confusing.
For both equations, we're looking a set of points $(x,y,z)$ in 3D Euclidean space. The first equation doesn't depend on $z$, which means that the cross sections parallel to the $xy$ plane will all be exactly the same. So, you can pick any cross section parallel to the $xy$ plane, figure out the 2D plot, then "extrude" this plot along the $z$ axis. For instance, you could set $z=0$ (which is fine, since your equation doesn't depend on $z$); the resulting equation describes a circle in the $xy$ plane. Do the same for $z=1$, or $z=\pi$ or in fact $z=k$ for any value of $k$ - and they will all look like circles lying in the $z=k$ plane, centered on the $z$ axis.
For the second equation, the story is much the same - your equation doesn't depend on $x$, so the cross-sections parallel to the $yz$ plane will all look the same. Thus we pick any constant value for $x$ (say, $x=0$, $x=1$, $x=k$, etc), plot the figure, then extrude along the $x$-axis.