Don't forget to say "please!". :) The best way to ask this question would be, "Could you please explain the two sentences?" A direct statement in English can come across as rude. Anyway... I've found the page you're looking at, and I worry that you're biting off more than you can chew. When you start learning conditionals, you're advised not to put a modal after "if". This is because conditionals deal with cause and effect. When you see a modal in the "if-clause" (eg. in formal business writing), it becomes a polite request. This is what the webpage is trying to explain to you. The main thing to remember is that modals do not automatically go into the if-clause, and this is where many students make mistakes. Hopefully that answers your question and shows you how one of the sentences is quite absurd.

I agree with peachey on it