To see all of the content within a department site, or Group, and to create new content, you will go to the Group or Groups that you have access to. To do that, you can click on the Groups tab in the admin bar at the top of the screen. This will send you to a listing of all the groups you have permissions to edit content in. If you believe there is something missing from your list, contact Mark Mende email@example.com.
To view all of the existing content in the group and create new content within your group, click the Nodes tab on the right, which will send you to a listing of all content in that group. By default, it will be organized the date of the most recently edited/created content. You can also sort by the title of the content, the type of content and the author. If you click on the title of the content, it will take you to the content. There are tabs to the right of each piece of content, and you can select Edit and it will send you directly to the edit environment for that content.