2
You can go to sysadmin=>blocks
below the block listing you can create custom blocks and enable them... (you would want to use center block to present a whole page)
OR
use a module like freecontent, ipages, tinycontent, etc.
Most of these allow you to upload a page to your server and then link it. Once linked, the module will wrap it in your XOOPS templates.
I prefer freecontent myself.