Chapter 5 marks the begining of Ender's acceptance into his launch group, when he discovers who to hack into the computers ("desks") and launches his attack against Bernard and his gang who have been ostrasizing Ender since the launch.
Ender notices from afar that Bernard seems to pick on anyone who seems weaker than him. Instead of attacking in public, Ender, knowing he is smaller and will always be an easy target, launches an attack through the computer system, but creating a profile he whimsically names "God."
He then begins to circulate messages to the entire launch group as a passive aggressive attack on Bernard.
In addition to figuring out how to create a profile named "God," Ender learns how to send a message that automatically signs Bernard's name. Though Bernard (and everyone else, likely) suspects it is Ender who has cracked the computer system, his plan works. Bernard's power in the barracks is significantly weakened, and Ender begins to find others in his launch group to connect with.