I should probably just link you to the Secret Sections page, but since I'm bored and feeling nice I'll make a list for you:
SECRET SECTIONS YOU NEED TO FIND:
Happy Developer Home
Mystery Line 1 (Red)
Mystery Line 2 (Green)
Remember that you must COMPLETE the secret section for it to count. Simply touching it will not work. Also, you can find Blank really easily by using the commands /remove then /skip in your VIP server. Good luck!