You have to be the leader of the squad Rafe. If I remember right, it has to be a bmp picture, 64x64, 256 colors. Load-up the game on-line, click squads, then upload nose art. Browse to the folder you have stored the picture in and click it to upload. It will load quick, seeing as its only 6KB. Then you wait till it gets oked, and added.
Good Luck !
Maddog Joe