Well, if you have an image of who is your character you should start threading. If you want your character to be in Lhavit you should start in
this thread, with the date on which your character came to Lhavit. If he was born there you don't have to do this, but you should send private message to storyteller of the city (Legion in this case).
When you finished that you can start posting. If you have trouble with finding people to thread with you can join an open thread (
this is the only one I can notice currently, but somebody might open another and you can open one yourself). More common way is to open a thread in
Matchmaker forum and state what are you searching for. Eventually somebody will ask you for a thread.
You can also do solo threads and flashbacks. Flashbacks are memories of your character's (that's solo flashback) or your and some other characters together. People usually flash out some big points in character's life or meeting some people that should be friends of their character in present. Solo threads are threads involving only your character and NPCs (non-player-character), so those can be job or class threads or some flashbacks about him or his family and similar.
Hope I helped.