OS X Lion introduced a new way of scrolling, but it is completely opposite of the typical type of scrolling that most people are used to. However, this can be extremely frustrating to people switching to Mac or simply upgrading from Snow Leopard to Lion. Now, if you use the scrolling for a few days, you should be able to adjust to it over time. However, for people who can't adjust or often switch between their Lion Mac to a Snow Leopard/Windows/Linux machine, Apple has included a way to return the scrolling to its pre-Lion state.
Step 1: Open System Preferences