You can align a group of photos, graphics, and text on a page. While on the page spread click on one of the objects on the page. The editing frame will appear around the object.
While holding down the ctrl key on a PC or the command key on a Mac, click on the other content on the page. This will group all the content together surrounding it with the editing frame.
Here are all the things you can do with the objects within the editing frame:
Check out the video for using the alignment tools: