with small pockets like these 77s it's a good idea just to limp, to watch the flop very cheap. if hitting the set on the flop, like here, I would check to let your opponent with an AX make a bet and than call.
On turn I would check again and wait for the raise to rereaise. When you get reraised be aware of your opponent having a street, with pocket 8T, which is not unlikely, because of your preflop limping
On river I would bet and when it comes to reraise you have to choose if you give your opponent the street or a higher set. I think in most situations, you're winning with hitting the set, and such a board