button. Dropdown boxes invite the highly-recommended use of headline formats, like H1 and the ever-populer H2.
button. You should be prompted to select from a gallery or to upload a new image. This option is a little tricky.
button expands your work area and may make your work easier.You may want to fiddle with some of the settings for the content, like whether users can post comments, or the order in which items appear (called "weight") but you don't have to. You may "preview" your masterpiece or simply "submit" it. Depending on the item, it will either become immediately publicly available or may be submitted for moderation by the appropriate person.
Well, mostly. If you want to find what you wrote, and it does not appear anywhere you expect to see it, you can always find it in the administer>content link. Some items, like comments, forum posts, and book pages automatically appear somewhere useful. Others, like "pages" need to be added to a menu or a link for anyone to find them.