Cornell's Confluence site is located at: confluence.cornell.edu. Getting started with Confluence begins with gaining access to the service and if you not already been given access to a space, requesting a space. See What is a Space? What is a Page?
Attachments are files that are included on a specific page including images that appear on the page. Any type of file can be attached to a page. When you attach a file, you can link to it from that page or from other pages in Confluence.
The pages within a space are organized in a tree structure, where each page may have one or many child pages. You can see the current organization for your space by selecting Pages from the menu on the left side of the window. Clicking on the arrow next to a page name will display the child pages for that page.