I want to change my computer operating system, so I need to back up what I now have. Problem is that I do not have the software installed on my computer to do a back up. Where should I go to find a back up program that is either free or close to it?

Just burn the data you want to keep to a CD or DVD.

IBackup is a great online backup tool that has a 30 day free trial:
https://www.ibackup.com/ibprof/jsp/ibpr_signup.jsp?id=gianpiero_rondinelli
You can cancel before the 30 days is up and won't need to pay anything.

If you have more than 15gb Data Always provides unlimited storage:
http://dataalways.verazinfo.com:8079/lbclient?@IThelpp (http://dataalways.verazinfo.com:8079/lbclient?@IThelpp)