This page illustrates what's explained under Story Telling Tips.
To add in image:
1) Click the picture icon on the top menu bar in the editor window.
2) Click the Upload tab and then, on the next screen, do Choose File.
3) Navigate to the file you want on your computer and then Send it to the Server.
4) Next you'll see a variety things you can do with the image. The ones worth noting are Alternative Text and the Width.
> Alternative Text is a description of your image. The main folks using that field are seeing impaired people surfing the net with adaptive techology that reads the screen to them and, also, search engine robots.
> The Width determines whether your image fits on the screen. Full screen is 960 width including the sidebar content. 350 px is about the half of the content center pane. I often use 700 as my image width. Making sure the little padlock icon is closed keeps the image in proportion.