If you move down when the cursor is at the bottom of the screen, or move up when the cursor is at the top of the screen, you will see the text scroll up or down. This scrolling can be an effective way to display more text in a short file, but it can be tedious to move this way through a long file.
You can page or scroll backward or forward through a file, a screen or a half-screen at a time. To try out these commands on paint, you might want to add text so you have a longer file to work with.
Note that paging and scrolling are fundamentally different. Scrolling actually scrolls the cursor up or down through the text a line at a time, as though it were on a paper scroll. Paging moves the cursor up or down through the text a screenful at a time. On a fast system, you might not notice the difference. However, if you're working from a remote terminal or in any other situation where your system is running slower than usual, this difference can become painfully apparent.