Haven't watched it in over a year so I sort of forget but he went out with the rangers to go kill/ scout some wildlings. They found a group of them and killed them but the girl. Jon told them that he would kill her so they left, but he didnt have the courage. She tried to run but he caught her and tied her up. When they were walking she ended up escaping and leading him into a group of wildlings. They took him capture and were going to kill him, turns out they had like the head ranger with them as well (forget his names i suck with names). He knew he was going to die so he basically told Jon to fake a fight and have him end up killing him so he could possibly gain trust with the Wildlings. He does and they allow him to join. Now I'm pretty sure they going to attack the wall and like basically invade the south. Again havent seen it in forever, thats why I gotta watch them all again really soon because its almost April 6th!
You answered what I needed to know. I was mostly just confused why he went north. But now I understand. All of that seems to check out. Thanks!