don't know what to do

I'm the only lvl 10 in DW .......... i don't know what to do to create a RP with someone (rivalry)

find someone close to you and ask them if they want to have a feud, then do a rp and see if they respond if not there not really interested and you can try and find someone who will rp with you, you could find a tag partner and do like greeny and manic, let one rp while the other comes up with some new ideas or find someone who will give you half a rp which is there's and ask you to add your bit, you can also just pick a random person and rp for fun till you find someone to rp against.

Well Ringleader was supposed to have contacted you about doing a storyline together since you two are close in WS ( which is a far better indicator of you actual power than level is ) in fact you two are the only ones in the 20k region so you are more or less each other's only realistic choices.
I suggest you contact him via PM both here and ingame and you two work out what you want to do. I also strongly recommend you both find your way to the HELP section here and read the RP guide - it's one of the stickies in the section so you should be able to find it.