I picked up a cargo cover (interior over jump seats area) for my son's 98 ranger supercab. But in looking at where it installs, I'm not sure exactly where it goes or how it attaches to the rear wall. In peeking under the rear panels, there are square holes with smaller screw (?) holes above and below the rear window that appear to be where the cover fits. Are there brackets that go there or do screws just hold it? Thanks.