I have the files uploaded, and I got all of the forms filled in, but I keep getting this error message:

An error occurred trying to update the database
Table 'phpbb_auth_access' already exists

Can anyone help?

Check in your database for a table with the same ('phpbb_auth_access') name.

Sounds like you've either run the setup before or it's half worked before...

I'd agree with ognen's advice.

If that doesn't work, perhpas you could try downloading the latest version again....

Yes if you make sure that you are ok with losing any previous phpbb information then you can go in to your mysql database (in your mysql client) and delete all the tables with a "phpbb_" prefix to them. Then make sure your re-run setup completely without closing the browser, stopping, or refreshing pages.
-dk

Now I'm getting this error:

phpBB: Critical Error
Could not connect to the database

Does the database you are supplying exist??
Check capitalizations and things. Also check your mysql and php versions are up to date and that you are installing the latest phpbb version.
-dk

I'm installing phpbb v 2.0.4 The database for my Lycos account is dawgy00_uk_db

For non-ODBC databases the database server is typically localhost ! So you have following fields:
-database name: dawgy00_uk_db
-database server: localhost (or 127.0.0.1)
-username: typically username for your (Lycos) account
-password: for the initial administration account
"Domain (or server) name does NOT include http://! Enter just the domain name, eg. www.mydomain.com and NOT http://www.mydomain.com/. "
Good luck