WE can lift the top but do not know how to support* it

My guess is something is missing. I've seen 2 different systems. One uses gas struts. Just lift and let go. If you have the gas struts, they may be week and need to be replaced.

The other system uses metal tubing that is hinged at the top, bottom and middle. When the roof is down, it is folded and when it is up, it is straight and goes into a locked position. You just have to push the middle horizontal bar forward to lock it.

Do you have any photos you can post? The struts would be outside the canvas if you had them and the metal tubing would be inside if that was the system you have.