If you have been assigned an Omeka-S exhibit for a class, you will receive an email from Digital Library Technologies Group (@ Dartmouth) with a log-in link and instructions for claiming your account. If you don't see the email in your inbox, check your spam folder.
Once you log in, you should see the "back end" of Omeka-S, with a link to the project site for your class. Click on the "pencil" icon next to the site's title to start uploading items and creating pages.