I think to change your VMF name, you must re-register under the new name, thereby becoming the newest "newbie".
To post an image, click on FAQ at the top of the page. It explains it better than I could. You do need to have a place on the web to "park" the image. I use the MustangMods site to host my pictures. To see where others put theirs, right click on their pics, click on properties, and it will tell you which site they use. Have Fun!