I'm not teacher but this my suggestion as I know :
he , she , it = has
she has a beautiful cat .
every one has to clap.
it has a stormy weather .
he has to study hard this holiday .
I , we , they ... = have
I have to go .
we have a lessons after the break .
they have a great culture .
had in past
If i'm wrong , correct me . it's my personal effort .