Gauze or scrim? Gauze might be very flammable. Do a flame test on it before attempting to use it.
After that and if safe to be using, think of it as scrim material with various purposes. It can be invisible when lit just so, or almost solid from other angles. It can hold together scenery such as foliage on a drop so you can have two dimensional branches without other support to them, yet be almost invisible or be bunched up such as in a large scale powder puff effect or dress material. If thick enough in fiber or overlapping, yet has stretched holes it can be used as a sort of erosion cloth for textured scary cob-web like effects.
How to attach it - since your post was not that clear? Mostly sandwich it between layers of plywood, laminated at the edges to other things or against a more solid fabric, at least fold it a few times before you sew it.
Main question is what to you want to do with the gauze in scenic design or anything else?