strut braces are supposed to provide some improvement to the handling of a car. The theory is that the brace stops the suspension mount points from moving relative to each other, thus limiting camber changes under load.
installation is rather straight forward. First remove the nuts from the top of the strut, then place the bracket over the studs, re-install the nuts and tighten. Do the same with the other side, then adjust the bolts in the bar to the length required, tighten the lock nuts and install the bar. There should not be any tension or compression on the bar at rest. The purpose of a strut brace is to only hold the strut towers where they are, not pull them in or push them out.