In my limited experience almost all Gibs look similar as they are simply a long tapered, trapezoid cross-section, shaped rod. If you can see the ends then the large end is the end you push the gib "in" with for a tighter fit. So you have to back the other end's screw off of the small gib end first to allow the gib to move inward. Its function is to trap the gib once you have it adjusted. Then turn the large end screw in to push the gib in to the ways to make it a tighter fit. Then re-tighten the small end screw to keep the gib from moving.... as the slide is moved back and forth during cutting. If you do not the gib will commonly slip back and forth between the two screws. The large end corner of the gib is trapped under the screw head or other mechanism to make sure it can push on the gib. The small end of the gib is also trapped under its screw head when tightened down, but sometimes it does not stick out well and the screw head will slide up along side the gib edge (if the screw is loose) then pinching the small end of the gib against the way. This is bad as it means a single point point (end) of the gib is pinched into the way and so the gib-way sliding does not work well. If it is working properly, then you can use the small end screw to push the gib out, to a looser gib position.
In my older lathe the large end of the gib has notch cut in it and the screw head fits into the notch. So the large end screw can move the gib both in and out of the way cavity. This is nice if it is a tight fit in the notch, but a locking screw of some sort is still needed.
I have also found on my CNC mill one of the best ways to determine if the gib is tightened just right is to measure the back lash. If the gib is to tight, the backlash goes way up. As it is made looser the backlash goes down. However, if it is too loose then the table can twist and is not always at 90 degrees to the table movement. So the procedure I use is to loosen the gib to the point that the backlash will no longer decrease. Then tight it just until the backlash starts to increase. Then check the back lash at other points along the stage travel as the ways are not perfect and their maybe other locations that are more or less tight! On my mill the Y table, I think, the ways are out of parallel by quite a bit and so the backlash can be significantly different at different points along the travel! A compromise is required! On a non-CNC you can "feel" the tighness and make a first guess. This is harder to do on my CNC due the stepper motor cogging. So I use the backlash method.
Good luck.
Dave
