Contacting one of the River Campus Libraries' Outreach Librarians is a great way to get started. Stop by the Q&I desk inside Evans Lam Square, or send an email (see this directory).
Installing Omeka at digitalscholar.rochester.edu
How do I get Omeka?
Omeka comes in two flavors:
Omeka.net, from the Corporation for Digital Scholarship allows you to quickly create an Omeka site that they host and administer. This service is free (although there are paid options), however there are some limitations in customizability, plugins, and themes.
Omeka.org is the flavor that you administer yourself. You can either download and host it on your own hosting service, or through a tool such as MAMP, or through the University of Rochester's Digital Scholar service (see this tutorial).