Inside _system_ folder create a folder with this name: themes
then, inside the themes folder, create folders like this:
theme01
theme02
.
.
.
.
theme12
R4DS can hold up to 12 themes, no more, can be less.
Each folder represents the theme number, so pictures in theme01 folder will be theme01, in theme02 folder becomes theme02, and so on
Place the 4 pictures (must be in bitmap format, no other format supported) in corresponding folder. Make sure they are named as follow:
BCKGRD_1.BMP for topscreen background while selecting games
BCKGRD_2.BMP for touchscreen background image while selecting games
ICONS.BMP for main menu icons, including the background too
LOGO.BMP for topscreen image in main menu
THEME.INI for the theme itself initialization. Without this the theme will be screwed, since it contains the font color, version number, author, etc.
try it, it should work, since I'm looking at my R4DS theme folder while typing this for you.
P.S.: dare I say you've just bought your R4DS? My nephew just bought one and it doesn't contain any custom theme too