Generally speaking if you're entirely new to RPing its better to look at other RPs and maybe join a few so you can get a feel for it before making your own. You might find that doing that makes things easier and it'll allow you to create a RP of your own more in line with what people expect. In any case the only real reason I dropped by was because you were curious on how to post an image. If you look towards the bottom of the page you'll see a "Formatting Cheatsheet" with a toggle button. Hit the button and you'll see how to do a lot of things in terms of coding on this site. The way to post an image specifically is as follows.
[img]X[/img]
Replace the X with the url of the image. You can get the image by itself by right clicking on it and clicking "view image"