Writing a zone for a dyrt mud is a fairly simple process.  All you need is a 
text editor, a little spare time and a lot of imagination.  You can ask any 
developer to mail you a current zone to have as an example.  Contributing a 
zone will earn you 3000 points per room for mortals or 100 levels per room for
immortals.  Therefore, if you have a 30-room zone, you will earn either 90,000
points or 3000 levels by donating it.  Again, remember that you MUST either be 
the author of the zone or have the express permissions of the author in order 
to contribute a zone.