Pretty simple!

The person above you has asked a question and you just pick which one you would rather. Once you've given an answer you post your own question and so on :3c. Doesn't have to be "would you rather" it can also be a sentence that has two options.

Would you rather:
Travel into space or Travel to the deep oceans?

Spacee, the final frontier.

Would you rather: Mushroom pizza or Pineapple pizza?