The captioned image snippet is the one you will use most often to add an image to your site. This snippet does not have specific image dimension requirements, but it will not allow you to add large images to your site. This snippet will auto-format the image to the right side of the page. If you add captioning, it will appear, but if you do not, the space will not show on the published web page.
Here's an example:
The Truth About Cats
Two lovely cats sleep in the sun.
Cats are deeply misunderstood creatures, victim to many cultural stereotypes and media propaganda. Starting with 1961’s Disney classic, 101 Dalmatians, which depicted two Siamese cats with malintent, cats, especially Siamese cats, have been treated as if they were involved in mischief and secret assignations of the highest kind.
In taking the example of the Siamese, the breed is not moody or mean, they just tend to choose a favorite human. Who could blame them? Domesticated cats are both predators and prey — choosing friends for them could be a matter of life or death.