First of all, welcome to WCO!!
Hope you have an amazing time here!
For the question, you have to submit the character to RC! To do this, you click on the RiverClan/[whichever clan you want to add a chara to] tab on the top of the site. Then below the High Ranks (lead, dep, med, med app) you click on 'Add Character'!
From there, if you want a character born in RiverClan/[insert clan], then you should select "My cat is a new member of [clan]"!
This screen should pop up:
First thing you'll want to do, is set the prefix to "pending"!
Then you can fill out the rest of the info, and then your character is pending for approval from a High rank (But you can start roleplaying them the moment you submit them!)
And, huzzah! A character!
I hope this helped, and if you're confused about something then i'll try to help with that too
// @
Moonandstars