Hi King_Sling2004, a URL is a web address. It stands for Uniform Resource Locator. It is a means of naming documents or locations on the Internet.
To use Instant Messaging, you choose which one to use and you can have more then one. Go to these sites and there are others that I do not know where to download them.
www.yahoo.comor
www.msn.comThere will be an option for messenger that you will click on. You will be taken to a site where you will have the option to download the software. It is recommended when you start the download, to run the application. That way the software will do all the work and once completed it will be loaded on your computer.
I did forget one item. If you have a hotmail or yahoo account, you can use these for your username or you can create one at the time.
I hope this helps. Please let me know if you have more questions.