I cannot find the pinned help topic about posting code

It’s About the Python Help category

See also Pinned Topic -- How Do We Always Keep it Pinned? - feature - Discourse Meta. Basically, for Discourse, a “pinned topic” is something you should read at least once. When you’ve read it, it becomes unpinned for you and starts to go down the list of latest topics as new topics are created. (To get a list of pinned topics, search for in:pinned with the search button.)