It is in a slightly odd place. Click on your name in the top right corner. Then click on help(it is to the right of the about box in very light letters.) Here

It is in a slightly odd place. Click on your name in the top right corner. Then click on help(it is to the right of the about box in very light letters.) Here is a copy that is even easier to find: Blank lines separate paragraphs. Text after a blank line that is indented by two or more spaces is reproduced verbatim. (This is intended for code.) Text surrounded by asterisks is italicized, if the character after the first asterisk isn't whitespace. Urls become links, except in the text field of a submission.