does anyone know how to put a new cover on the rear sunroof of my 2000 legacy gt?

2000 leg gt,

 

You are most likely looking at quite a job to install one. The only manner that seems to be possible, would be to drop the headliner from car. At that point you'd be able to see what is involved in reinstalling the sunroof cover, as it attaches to the sunroof mechanism, and is obviously larger than the sunroof opening in the headliner. The A,B and C Pillar covers would all have to come out, as well as the sunvisors (rear view mirror ceiling or windshield mounted?), overhead lights, assist straps, seat belt anchors?, and ceiling plugs. At that point the headliner would simply fall down, be removed from the car, and let you see exactly what you'll need to do. Good Luck if you decide to tackle it!

Mine jumped the track and I was able to "snap" it back into the track. What happened to yours that you need to replace it?