The following should be placed at the bottom of the blocked user's talk page (click "edit" at the top of the talk page):

==Blocked==
{{blocked talkrevoked|time=block expiry here|reason=your reason here|endtext=your end text here}}
~~~~

Replace "block expiry here" with block expiry; otherwise "indefinite", replace "your reason here" with the block reason with no periods at the end, and "your end text here" with your end text; otherwise, "Thank you."