Shirt colour can be whatever you want, but if you pick a common colour you'll get a properly-coloured shirt icon next to your team name in various displays. Examples include yellow , light blue and dark . If you have two options, list them both. For example, "blue or white" will show like this: /. If you get the "unknown" shirt , this means that your colour is not supported.
If you have suggestions for additions, changes or other improvements to this online help, please send them to greg@zuluru.net.