Session Stealer Help (Force OP)

I was wondering what information do you need to have in order to force OP.
And also:
Does it have to be your server?
Do I have to port-forward even if I'm trying to force OP myself in another server?
What is the difference between target port and listen port?
What if the server doesn't have the port beside their ip. eg. 69.134.421[none of the :22560 or whatever]?

I'm a complete noob at this so ya...