ah, first time nerves eh ! all the more reason to jump in with both feet, next time you won't be scared.
either you can make up a short description yourself, or ask rse for one. the most important thing is the title you give your thread ; take a look how the others are named and follow that convention, otherwise it won't be properly indexed (you should use just Ralph Sir Edward for the thread title, not "sir sir rse".
). i imagine you could think of a pretty hilarious description yourself, it doesn't have to be very long.
another tip, attach the file using the paperclip icon, but DO NOT "insert attachment" with the attachment manager thingy afterwards.