Hi there, welcome to the forum! There are a few ways you can kick things off, but your best bet for getting your character rolling would be to join the faction discord that you're interested in writing your character with and reaching out to some of the writers there. Faction threads can be a great jumping off point since the premise is already written and all you have to do is respond to it.
You can also put up a LFG in the LFG forum if the faction discords seem too daunting, and explain the kind of roleplay scenarios and stories that you're interested in.
Or, the third option, you can always put up a 'first reply thread' and as the tag suggests, whoever replies first to your story thread will be your partner for the duration.
Hope that helps and if you have any more questions, feel free to reach out.