I would suggest trying to find existing RPs that are close to what you enjoy and join one of them to get started.

As others have said starting an RP is a lot harder than joining one, especially when you're new.  Join one.  Find some writers you like.  Get to know them.  Learn a bit about formatting (this place is weird as hell that way, I still have to pull up the little helper thing more often than not) on this site so your Interest Checks can be easier to interact with.

Starting an RP of your own means you are competing with everyone who already has one open or is about to open one.  As a brand new user you are at an inherent disadvantage in that since no one knows you, you don't know anyone, and you have relatively niche interests.

Plus as Gravity said things can move slowly.  Sometimes the community is in a slump or there are enough big RPs active that no one really has time for a small one.  I can't tell you how many RPs I've been in that died before they got past like three pages of posts.

Bear in mind too that as many users as we have here and on the Discord more than half of them don't actually RP, rarely RP, or divide their RPing between this site, other sites, Discord, and PMs.

Patience is required.  Even the best GMs and RPers here have a hard time sometimes.