Mysqli error

I'd like to test out Omeka for some possible future projects. When I install it, I get the following message:
The Mysqli extension is required for this adapter but the extension is not loaded

I'm not a server admin, so I assume I need to take this up with the folks that administer my web server. Can you tell me specifically what I need to ask them to do?

You'll have to ask your server admin to install the mysqli extension for PHP5