ATLAS Software Installation
ATLAS produce many versions of their athena software. These should be automatically distributed and installed at sites however sometimes they don't work and need to be re-installed. While this should be done by ATLAS central it is possible for site admins to do this if they wish.
The page where you can see what software is installed at your site and request additional releases can be found: 
Getting the correct priveleges
Before you can request installation you need to register. Click on the User Registration link on the left side of the screen:  You want to request that you are a user and be able to view protected info and post Post installation requests. This request will be sent to Alessandro de Salvo for approval and he may contact you to confirm who you are.
Requesting an installation
Once you have the correct priveleges you can request an install by clicking on the Request an installation link on the left side of the screen: . The form is fairly self explanatory. The type of install you want in general is validation. If an install job has failed at a site, the install will be resubmit every 24 hours.