How do you get colors like black for behind xmb waves?

[occ31191]

i havent been able to find any to download and i kno they have to be somewhere. when people have previews of their waves it has black behind it

[VenomIreland]

Would anyone mind telling me how to apply that? Or better yet, add a black colour to the roster of other colours without overwriting them?

Sorry for bumping the year old thread