iASP, or iTools, which includes it, is some kind of an upgrade for the Apache webserver running on every OS X. Apache is an opensource webserver, and one of the best webservers available. When you start "web sharing" in your System Preferences, the Apache server is started, serving all files in your "Sites" folder to the world. This means that from this point on, your system works as a (tuned down) webserver. So, first, make sure Apache is running after you installed iASP. I know that there is a configuration tool for the iTools somewhere in their installation folder, use it to get everything runnin, then write an ASP file in simpletext (I hope you know Visual Basic or J++) and save it with the ending .asp in your sites folder. Now, just open your IE, and open the page from your IP adress or localhost to access and execute the file.