Well Colleen,
By looking at your profile and user options here, you SHOULD login automatically when you return to the boards.
You might want to check your browser to make sure that "cookies" are enabled. (You can do this by looking in the "preferences" section in both Netscape and Internet Explorer.) If "cookies" are not enabled, the site cannot detect your username and password automatically... so you'll have to sign in for each visit.
Let us know if you need any additional help!