how do you access files from different workgroups?
Right, as peter stated above. In earlier OS types, different verbiage, but it's all the same. Imagine how complex the world of networking would be if you couldn't access computers/printers/files from different workgroups.... LOL
Anyway, a computer or node's "Workgroup or zone" is simply that ... just a name for organizational purposes. Sometimes they refer to a physical location within a small LAN. The workgroup name is sent, in a simple way, across the network, but more times than not, it is ignored (gateways and routers drop these bits). It's only really used across a P2P network so that your machine can display all of the Workgroups in your LAN....nothing more. Share permissions, etc cannot be controlled on a workgroup level. It's pretty pointless actually.
If I had a small LAN in my office that incorporated a few different "Workgroups" then I would be able (if connected correctly) be able to see all workgroups in the lan. They would all appear the same way your 1 workgroup does before you click on it and then see all of the computers.
If I had a OFFICE LAN using only P2P networking:
Perhaps one workgroup would be "HR" .. in this workgroup I could have nodes called "HR1", "HR2", and maybe a printer called "HROFFICEJET". Then on the second floor perhaps I would have a workgroup called "ADMIN" and have nodes called "ADMIN1", "ADMIN2" and a printer called "ADMINLASERJET". We are all connected on the same LAN and are using P2P. So, at the "ADMIN1" station, if I typed \\HR1 in explorer, a password prompt would appear (depending how I was logged in and the users existing on the "HR1" computer of course.) But, since Workgrouping is only really used in P2P networking, it then doesn't rely on what Workgroup you are in for anything.....just relies on the user permissions on the computer that you are trying to access.
In short, the answer to your question in the quote is.... "The same way you would normally"