Movie Maker Question

You'd probably need a photo editor of some sort, such as Photoshop, to enlarge the pictures (not familiar with Movie Maker, so I have no clue if it provides image scaling). However, you won't be able to enlarge the pictures enough to fit the screen if they aren't that big to start with; you'll lose resolution and the pictures will be blurry. It's easier to start with larger pictures and scale them down, if necessary.

Drag your image file into Collections. Drag it from there to the time line. WMM scales it to fit the movie. But it keeps the original aspect ratio, so if your picture is too narrow or too tall, it gets fitted to whichever dimension is larger. If you want it to fill the screen, you must crop it in an external image editor program.

http://www.online-image-editor.com/

If you don't have photoshop you can use this! Works pretty well...

Also, Gimp is a free photo editing software you can download. It's like photoshop (not quite as good) but it's free!