Faction Change

I want to use faction change, but i dont know what i need to do before i use it. How to keep my stuff?

Do i loose something, like items, gold, bank etc.?

you will not lose aything. Go here: https://www.warmane.com/account/services > active it

then you just need to log-in and you will see your chaarcter will be able to change faction once on character selection screen

Okay thanks. And will i be able to choose race?

yes, you will be