I think you are confusing reviewpost with vbulletin's admincp.
The admin control panel for reviewpost is located right under the navbar (on the right side).
Also, you can go to your admin area here:
http://www.domain.com/adm-index.php
Now this is assuming it's installed in your root directory. If it's not, just point the adm-index.php to the directory/folder you installed it to.
I've also attached a small screenshot of where to find the admin link.