Ah feel for the sweet face of a ball python - it happens to a lot of us LOL
First thing, big breath, no panic and don't buy too heavily into the "ball pythons are crappy eaters" hype too much. Sure some of them are, most of them because they aren't being kept quite right but generally most get going just fine. If they didn't eat, they'd die off and heck where would all these ball pythons be in our collections.
You can make that glass tank workable with a few modifications or you can run out and get a plastic tub, your choice. Just set your new BP up in whatever way can be done quickly and efficiently and hits the goals of...
- warm side temp 90 (no night drops needed)
- cool side temp 80
- humidity 50-60%
- at least one, preferably two dark hides that are barely bigger than your snake is coiled up
- snake safe substrate
- non-tipable easy to clean water dish
- quiet area of the house so the snake can settle in (he should like any new snake be in QT anyways)
- you may want to cover the outside of the glass enclosure on the sides and back to offer a bit more privacy to these shy snakes
- don't handle or try to feed for a week to allow your new bp to check out his home and get comfy
That's really about it. Set the snake up, leave it be and in about a week offer it an appropriately sized prey item. Try to stick with the type of prey and the manner of feeding this snake knows for at least the first couple of feedings, then assess where the snake is at, how things are going and start to make any changes slowly.
All of this assumes of course, that you purchased a healthy snake from a reputable breeder. If you didn't, well that's another whole ball of wax.