If the crib was not originally designed to have a drape over it, it will be difficult to create one, especially one which will fit where you want it to fit, and not come loose, or stick in your eye when you bend over to lift the baby. You could get a couple of wooden rods or dowels, and fix them over the crib in an inverted "L" shape, but it would not be particularly easy to fasten the drape to these. The traditional way is to have a metal rod in the shape of an inverted "L", or a half-arch, which is threaded through a channel stitched along the middle of the drape. Something like a small rubber ball or cork would have to be stuck on the end of the rod to cover the sharp end.
Altogether, you might be better off deciding where the crib is to stand, and screwing a bracket on the wall above it ( like a small bookshelf-bracket) and putting the drape over it separately above the crib. Again, protect the end of the bracket so it cannot injure anyone.