you need to use FEAR and check the "Is Complete" and the "Single Player" checkboxes (assuming it's a single player map)
then you select the 'build plug(in)' and build your plugin.
BUT BEFORE YOU DO THAT it would be really good if you reviewed one of the map making guides to make sure you have all the little pieces correct - like the text string with your map/level names, flavor text, pregame image, overhead map, etc.
Cydonian's mapmaking guide is a really good concise guide to those last critical steps.
Skip to the section called "VI. Overhead Map, Pregame Pic, and that String tag" - it covers the things I mentioned, PLUS reminds you about thinking about setting the right parameters for fog, lighting, wind, ambient sound, adding rain or snow, etc. I made a map once that I like but forgot to put any ambient sound on it and it bugs the heck out of me everytime I play it... it just feels wrong. Even a desert should have *some* background sound.
It also reminds you how to test that y our plugin actually works before you upload it for others to try. (hint: If you don't move/rename your local folder you'll never know if your plugin works or not)
Ps. How to post to the Tain? If you are logged onto TheTain (not the forums) there's a link near the top o fthe page to 'submit a file'. (and make sure you zip your file before you upload it) from the forums, click the 'sitemap' link for the same 'submit a file' link.