Posts:
Posts > Lists all of your posts, whether published or just drafts.
Add New > Create a new post.
Categories > Lists all your existing categories, where you can edit or delete existing categories, or add new ones.
Post Tags > Lists all your existing tags, where you can edit or delete existing tags, or add new ones.

Media:
Library > Lists all your uploaded images. From here, you can edit captions and alt tags that will affect every instance of the image on your site.
Add New > Upload images en masse to the library, to be used in any post or page.

Links:
(used in widgets/sidebars)
Links > Lists all available links. From here, you can edit or delete existing links.
Add New > Add new links.
Link Categories > Organize your links here. (For example, you can group your links into research institutes vs. conservation institutes vs. sponsors.)

Pages:
Pages > Lists all of your pages, whether published or just drafts.
Add New > Create a new page.

Comments:
Lists all the comments on your site, including comments queued to be approved. From here you can delete and even edit the comments.

Appearance:
Themes > Change layouts and colors, headers, etc.
Widgets > Control what appears in the sidebars and footers.
Menus > Create custom menus to use in place of the default “page-based” navigation.
Background > Change the background color or upload an image. (Not available with all themes.)
Header > Change the header image that appears behind your blog title. (Not available with all themes.)

Plugins: Add, remove, activate and deactive plugins. (examples of what plugins do: control spam comments; track statistics; cache pages for your users so the site runs faster.)

Users:
Users > Lists all your registered users. From here you can edit their role (subscriber vs. contributor).
Add New > Invite new users to your site.
Your Profile > Edit your profile, including your nickname, password and personal info, as well as the color scheme of your dashboard (sadly there are only two options).

Tools:
(Advanced, you probably won’t ever need any of these)
Tools > Scripts to help you pull RSS feeds from other sites and convert them to posts, and to convert categories to tags, and vice versa.
Import > Scripts to help you import blog posts from other sites, if you are converting an existing site.
Export > Script to export your site’s content so you can import it to another site.

Settings:
General > Change the title and tagline of your site, your admin email address, and your timezone.
Writing > Change the default height of the editing box on edit-post and edit-page and set default Categories for new posts.
Reading > Set your front page to display something other than your latest posts, as well as how your own RSS feed should appear to subscribers.
Discussion > Control comment settings.
Media > Set the defaults for the sizes of your images.
Privacy > Set to block or allow search engine bots to your site. (This is where you will “launch” your site.)
Permalinks > Control how the URLs will appear for your blog posts. The default is to display posts with year/month/day/blog-title (ex: https://aam.pmcarlson.com/trouble/2011/05/16/hello-world/) It’s a personal preference–I prefer year/blog-title, but if you anticipate ever duplicating a blog title, then separating it by date would be useful.