How do I add an image to my page?

The best way to add an image to a page is simply to go to File, then Place. From the Place menu just choose our image and InDesign will place it on your page where you can then work with it.
You can also copy and paste images from other programs, like from word and from Photoshop but you may experience a loss of quality, especially when resizing.
Finally, you can also take screenshots and dump them into InDesign. You can do this by setting up your screen, pressing the Print Scrn button at the top right-hand side of the keyboard, and selecting paste in InDesign. (On a Mac, you must go into Applications, Utilities, and open the program Grab. Take your screenshots from the Capture menu, which allows you to select a window, the entire screen, or areas you select yourself.)