SQL Mail provides a way to send EMail from Micosoft SQL Server. The focus of this FAQ is configuration of SQL Mail. There are other ways to send Email from SQL Server. Links to articles about these alternatives to SQLMail are listed at the end of this FAQ.
This FAQ doesn't contain detailed instructions for configuring SQL Mail. Rather, the FAQ will list several valuable links where you can learn to configure SQL Mail.
SQL Books Online is a valuable resource and should be the first place you look for information about configuring SQL Mail. Here are the main links. Many of the pages referenced have additional links.