After I install XOOPS And try to access the Admin Menu it says "You don't have the right to access this area".

What can I do???

You're not alone.
There is another thread on this, but no solution by now.

See "Admin can't do ANYTHING" :
https://xoops.org/modules/newbb/viewtopic.php?topic_id=46500&forum=1

I guess it only works with PHP lower than 4.1 (that is, 4.0.something or earlier). I'm trying to find out if it could work with higher version.

I've noticed that lots of sessions are being created in the database (using MySQL 4.1). I believe that the problem is linked to the session management in recent PHP releases. But I have not validated this with any XOOPS knowledgeable person.

I've installed XOOPS 2.2.3 Final.

I'm suspecting file class/xoopssecurity.php by lines 96 and below (function validateToken).

Do some skilled person read us ?