You are now creating the description for a tag in the Signpost tag index.
A description item for a tag looks like this:
==nameofthetag==
A description of what the tag is about.
Creating the description for a tag is easy: just hit the (create) button at the end of the description of a tag in the index (as you appear to have done). The description to a tag should convey, in the length of a few sentences or a short paragraph, an understanding of what the topic is. If necessary, try also to convey why it is important. Oftentimes tag descriptions copy from the introductory text of the associated help or project page.
The title of the section has already been created for you: no further effort required!
After creating a description there is one more thing you must do. After you are done creating your description and saving the page, paste the following parameter in this tag's entry in the index and save the page:
