They're, Their and there

When should you use they're? Its they are but joined Eg: They're all okay. But with they are it will be they are okay.

They're coming for dinner tonight.

When should you use their? Its when your talking to them or themselves Eg: the parents are proud of their child.

Their Hats are olden style.

When should you use there? its in or at the place Eg: "Its not there"
"Are we there yet"