The key thing in asking for help is to show some initiative. If you are lost you can start by defining the words/concepts that confuse you.
What is a "domain set", what is a "range set". Google those terms, find favorite tutorial sites that give clear explanations. Copy and post the definitions, explain them, ask questions if they don't make sense. By the time you do that it is more than likely that if you still cannot solve the problem you will have ideas of what is confusing you.
In short, to pay the piper here, show effort. Thus I have learned.