Add in whatever text you want. It works pretty much like any word processing app. (Ignore the Edit with Fusion Builder button.) As you work on the page, you should click Update.
Then you can see the page by clicking Different (in a new tab. You want to keep the backend page open for more edits). You will have to reload the page to see the changes.
Add photos by clicking Add Media, which gives you the choice of inserting something from the Media Library or uploading something from your computer. Here, I added something from the library, aligned Right.You can also select different sizes you want to insert. You see that the text wraps around the photo. If you Align None, the image will split the text above and below the image.
Below, I added a gallery of photos. It appears on the page as a grid of thumbnails and expands to a lightbox when you click on a thumbnail.