Once you understand what output impedance means and what to look for, it should be pretty straightforward to connect a single cabinet to your amp head.
All you need is the correct speaker wire, and a cabinet that supports equal or more power than your amp.
In order to hook up a second speaker, there are now two options for how you can and may want to do things.
Generally, a two speaker hookup is done in what’s called parallel. The + sides of the speakers are wired to the other + and the – are wired to the – sides.
With parallel wiring, the output of the speakers becomes half.
For example, 2×8 Ohm speakers is seen as 4 Ohm by the amp.
With serial wiring, the output becomes double.
For example, 2×4 Ohm speakers is seen as 8 Ohms by the amp.