Two ways to make the image smaller:
Crop: which cuts out unwanted parts of the picture, leaves the resolution and detail alone
Resize: Leaves all the picture intact, just makes the entire picture be at a lower resolution. It also maintains the same aspect ratio (ratio of the width to height).
I like to use the picture viewer/editor called ACDsee. Then if I want to make a smaller version of a picture, I click on
(type in the desired width, in pixels)
Save_as -> name_smaller