It’s truly as easy as this:
Cut the mesh to the size wall you want. Cut for the bottom, the 2 narrow sides, the 2 long sides, and the top. On the ground, lay in place the pieces of mesh. Using the heavy wire, attach the bottom and 4 sides together at all corners using a helical (spiral) type method (winding it in and out of the 2 pieces, like a corkscrew). Don’t attach the top yet. Put the cage in place where you want it because unless you have a crane, it’s not going anywhere once it’s filled.