Okay so I copied and pasted it. (I am so going to wear you out on this. Sorry!) Renamed it p51d_1. Now I have copied my .bmp file into the folder, overwriting the default. I can see it in the viewer. Looks pretty good actually. LOL. I thought I would mess it up but so far so good.
Is this what I need for it to show up in offline mode? Once I know how to get to that point I may actually try and do a skin for real....