You can email it to your friend
If your file is just a DesktopX theme, then it doesn't need to be a suite it needs to be .dxtheme
If you file contains other than desktopx, then it should be a .suite
Your friend can get and install
Theme Manager to apply the .suite
Your friend will need the other software to go with components of your suite (CursorXP, IconPackager, Windowblinds, etc) other than DesktopX.
wander over to the suites gallery and look at some of the descriptions - you'll get an idea of what can be included in a .suite
then look at the DesktopX themes gallery - click download on one and you'll see it's usually a .dxtheme