Add Item Menu

The Add Item drop-down menu allows you to add content into your current folder.  (This drop-down sometimes appears as "Add To Folder" if you are viewing content.)

Depending on where you are in the site, and what your access level is, you will see different items appear in the Add Item list. 

In the example below, the list shows a "superset" of just about all the content types you are likely to see within the site.

Each of these items have a particular set of information associated with them, and thus you will see a different Edit form depending upon which type of content you are adding.