I know this will get looked down on, and there is no such thing as proper english on the internets buuuuuuuuuuut:
You're is as in You are. For example: You're banned.
Your as in yourself. For example: Your paper has a lot of mistakes on it.
Their as Them. For example: It was theirs.
They're are as in They are. For example: They're going to ban you.
There as in place. If you go there, they're going to ban you.
Then as in time. For example: I was banned back then.
Than in comparison. My E-peen is bigger than yours.
Worse is comparative. You are worse than me.
Worst is superlative. You are the worst!
I think thats about all of them.