Join the eBay Developers Program and get your Access Keys. eBay Developers is free and you get 5,000 API calls a day just for joining. When you generate your application keys from your My Account page, note your Production AppID so you can substitute it in this tutorial where it says "MyAppID."
eBay Finding API: Finding Items by Keywords
You build a simple coldfusion application to submit a findItemsByKeywords call to search for eBay listings based on a keyword query. The code constructs a URL-format HTTP GET call that returns the results in XML format. The code parses the XML and constructs a simple HTML page with data from the call response.