If you have questions about using mojoPortal, you can post them here.
You may want to first review our site administration documentation to see if your question is answered there.
a mojoportal site has some additional custom profile properties.
how can I allow site users to edit them themselves?
Search for mojoProfile.config
This file lets you set who can modify what custom fields.
You should read this bit of documentation: http://www.mojoportal.com/userprofileconfiguration.aspx. It will help you get started on setting up custom profile properties and setting permissions on them.