So far, within the pages, most of the images are set off to the right, and the code to do so is
[[Image:Photo_Name.jpg|right]]
Adding that | symbol creates several options in wiki markup language, as you have seen with Categories where |LastName, FirstName is used for artists, for example.
If the image is fairly large, you can also do a thumbnail-with-caption approach, which you have probably seen on Wikipedia. Code for that is
[[Image:Photo_Name.jpg|thumb|Caption text]]
Pretty straightforward in the end, which is nice.