I’m no expert, but I would start by writing down for yourself the backstory of your character. Parents and family can be tricky - best to leave that vague - but what is your personality? what have you done? what do you want? all that. And no, being the all-powerful hero who Saved the Universe many times should not be part of that!
Now, read a lot. Start here
but also the Argent Dawn forum generally
and the Argent Archives
https://www.argentarchives.org/
Get a Role-Play addon that allows others to see the character you have written for yourself and look at what others have in their
https://www.curseforge.com/wow/addons/total-rp-3
Make a level 1 on AD, and just watch the interactions, and conversation and guild ads.
Check out guilds on the AD forums. Join any Discords that appeal to you.