The left column of the All Articles page (which is the default page of the Post Manager tab) contains the Category Tree, a graphic representation of your blog's categories and photo albums:

The top level of the Category Tree is your main page and is represented by the icon. The main page is the master category and contains all the other categories and photo albums in your blog. The Category Tree shows the relationships between the main page and its children — namely, the categories, articles, and photo albums it contains.

In the Category Tree, categories are represented by the icon. Categories can contain subcategories and photo albums; when they do, their branch contains a + sign. Click the + sign to view the folders it contains.

Photo albums are represented by the icon in the Category Tree. Like categories, photo albums can contain other photo albums and categories.

When you first open the Post Manager, only sub-categories of the main page are displayed. To see the full tree and all subcategories, by click the expand all link above the Category Tree. To conceal sub-categories, click the close all link.