vertex paint issue :/

Okej, so i made a texture for my 3d model, but i added some black dirt on it with vertex paint. My question now is, is there a way to make a UV of that vertex pain?
Or can i ad this to my existing UV?
and for some od reason my vertex paint doesnt show in the renderer.
plz help

Its not a render btw, its a screenshot of my work on the workspace

create a new picture assigned to the UV:s of your mesh, go to the bake menu in render options (or press ctrl+alt+b), select textures and bake it. Remember to have your target object active:yes: