The Sceptre output jacks are labelled 8 and 4 ohms. If you have one 8 ohm cabinet, plug it into the 8 ohm jack. Likewise with a 4 ohm cabinet.
However, the jacks are switched. If you have two 8 ohm cabinets, plug one into each jack, and both will be 4 ohm jacks (which is what you want, because the total impedance is now 4 ohms).
Ox, the Sceptre does not have a 2 ohm tap on its output transformer, and cannot be run safely at 2 ohms. You could wire the two cabinets in series, though, and run them from the 8 ohm jack.