except and unless

except and unless
how do you to use "except" and "unless"??
can someone help me??

Everyone went to university except me. (except + thing)
You can't get into university unless you do what your teachers say. (unless + requirement)

All the countries in the EU, except France, agreed to attack Russia.
Unless a country is in Europe, it cannot join the EU.

I ate everything except the candy.
You shouldn't eat candy unless you want to get fat.