The term broadband vaguely refers to connections faster than a conventional modem link. For most users, this means a DSL or cable modem connection. One of the most frustrating things about broadband providers is that they don't tend to tell you what kind of technology they use.
Most DSL or cable modems have an Ethernet port, requiring you to have an Ethernet interface on your computer, and as you saw in Configuring Interfaces and the Host-to-Network Layer, it's not hard to set up an Ethernet interface (in theory, at least). Unfortunately, not all providers send straight IP from the Ethernet port, so things can get more complicated.
For the most part, your setup depends on the kind of broadband connection you have. These rules ...