There are several website online that show you how to post a Craigslist Listing so I thought I would list them all out here for a quick reference.

Posting a listing with Video. Best I could find online.
http://www.wikihow.com/Post-Ads-to-Craigslist 

This is the "Official" Craigslist how to.
http://www.craigslist.org/about/help/how -

Very breif tutorial on submitting images to Craigslist.
http://www.bukisa.com/articles/37784_design-and-post-image-ads-to-craigslist - 

The eHow.com version. Clearly defined steps for posting an ad from start to finish
http://www.ehow.com/how_2221444_post-ad-craigslist.html -