I have a 4 ohm bass guitar amplier. So I can only run one 4ohm speaker cabinet and not 2 correct? If I tried to use a 4ohm cabinet with a 8ohm cabinet with the 4 ohm amp would that still work or would the ohms become less than 4?

From what I remember you can drive 8 ohms with a 4 ohm amp, but not the reverse.

If you parallel a 8 ohm cabinet with a 4 ohm cabinet your load will be 2.6 ohms…......so I don’t think I would do that unless you want your amp to overheat and maybe fail. If you parallel two 8 ohm cabinets together, then the load would be 4 ohms. You could however series wire them and get a 12 ohm load which would work. Search for ‘series’ and ‘parallel’ wiring on the internet and this should help you with ohm loads.