When a person in the drop-down box is selected, the showUser() function executes the following:
1. Calls the GetXmlHttpObject() function to create an XMLHTTP object
2. Defines an URL (filename) to send to the server
3. Adds a parameter (q) to the URL with the content of the drop-down box
4. Adds a random number to prevent the server from using a cached file
5. Each time the readyState property changes, the stateChanged() function will be executed
6. Opens the XMLHTTP object with the given URL
7. Sends an HTTP request to the server