The yellow and red hair are included in the 4 different color options, which you get to change during the character creation process. In MB, there are no restrictions against editing the default skins (which can be found in \\PlaneShift\\art\\textures\\races), but the modifications will be seen by you only - there is no utility to upload them to the server so that the other players may see your custom creations. Also, the changes you make will be seen not only on your own character, but every other character who chose the skin you\'ve edited.