Book-style illustrations are meant to be as easy as possible. After uploading an image, a thumbnail will be automatically created. With one line you link the thumbnail, add a caption, and beautifully reflow your writing around the picture.
The "code" for this is fairly simple:
![The caption goes here.](picture_file.jpg) The body of the paragraph goes directly under the link, like this. The picture will be placed off to one side, and the text flows around it.
What if you don't want inline illustrations, but instead want a grid-like photo gallery? Also very simple, group the pictures together (one per line) while leaving a blank line before and after the set.
This text will appear above the gallery. ![These](photo1.jpg) ![will](photo2.jpg) ![form](photo3.jpg) ![a](photo4.jpg) ![grid.](photo5.jpg) This text will appear below the gallery.
It does not matter if you write the post first or upload the pictures first. Either will work.