Thunderbird FAQ:

How do I install Thunderbird?

How do I upgrade to the latest version?

How do I save e-mail messages from my Inbox to another folder?

How do I setup junk mail filtering for Thunderbird?

How do I create custom filters in Thunderbird?

How do I setup Thunderbird (I have an existing account and want to move my mail over to the new server)?

How do I setup Thunderbird (if I've never setup my econ.ucsb.edu e-mail on this computer before)?

How do I setup Thunderbird 3.0+?