Now, to the part of your question "how to enter" ---> Simply click on above link --> Read the contest (I am asking for how many cookies were dunked from level #1 to level # 250) --> Guess how many cookies you have dunked --> You will see an empty comment box in the bottom of the page --> Simply click on it and write your guess --> Then click on "Reply".
That's it You are entered into the contest
Please let me know if you need further assistance / clarification. If you tap on "Type your Comment", you will be able to write back
All the Best with your contests! Have a great weekend!