Users and logins

Quick question:
I am creating a new sql server, on a server, and am not sure how to allow other users to access the database(s) on it.
we use the windows domain authentication, so each user has a user name and such. Do i need to create a new user for each person that wants to use the database? Or can I create a user on the server and specify which people are that type of user?
general user, power user, admin user, etc.
Or does each person need a login or user entered into the server?

thanks.

You just need to add the domain users to the SQL server and then assign the required permissions on the SQL server itself.

How would this work with using MS Access as the front end? if they open Access, is the user actually connecting to SQL Server? I haven't figured out how Access uses the SQL Server as a back end, yet. I am able to connect to it using ADODB, and make use of recordsets, but I am not sure that will be sufficient.