First - it is a necessary part of your car to keep it safe - you really should replace it

Second - its mounts should be obvious if you look along the exhaust system. Check other heat shields as well.

I suggest that you find the mounts and see if you can remove them - then get a new piece or repair the one you have.

You could shape a patch somewhat larger than the holes and use pop rivets to attach the patches. Use very short rivets designed to attach sheet metal together.