You can find all layouts available at the bottom of the design app.
There are two options:
1) Select "Smart Layout" and drag and drop your images onto the page for the system to automatically select a layout for you. Click on it again to see what possibilities it comes up with!
2) Click on the number of images you have planned for the page, and use your scroll bar to scroll left/right to see all available layouts. Click on the one you like and drag and drop your photos in.
