cache mechanism

My website is [login to view URL] and the company that we have hosting our website said, "I apologize, but I was forced to suspend the script /home/ent2010/public_html/[login to view URL] as it was causing a high load on the server, and due to it affecting all of the other accounts on the system, I forced to take immediate action for the health of the server. Unfortunately I do not have any specific recommendations for this script, however, in general, adding some sort of caching mechanism, where the script does not need to generate a new page with every request, helps to lower the over load that a script will cause. Likely the original author or support group of the software that you are using will be able to help you to understand how to add something of this nature." We need for this to be fixed so our website can be live again. And we need a person to ad a facebook "like" button and to help ad google adsense banners to our sight. This is a very simple project. [login to view URL] is a website that lets students buy and sell their textbooks from other students. It is a basic website. I am using codeigniter.