how is the victory celebrated?

Napoleon made a speech and a funeral was held for the slain. Then they had a two day celebration, which included songs, speeches, and the special treat of an apple for every animal.

they shot gun fire everytime there was a celebration.

Squealor used his propaganda to convince the animals that there is something to celebrate.after that they found a case of whisky in the farm cellas and drank it to excel thus breaking the rule which they changed afterwards when squealor fell off a ladder changing it.