We use should and ought to when we want to say something is a good idea.
Should is used more in conversation, while ought to is more formal.
Examples
Present
You have a bad cough. You should stop smoking.
It's a great film. You should go and see it.
You ought to call her. She's worried.
Past
You shouldn't have shouted at him.
He should have studied more.
They ought to have tried harder.
Now
I should be working now.
She should be helping getting ready.
They ought to be making the supper.
See also:
English Grammar Reference: Introduction to modal verbs
