How to call an external program from my site

Hello guys. Im very new to wordpress, but i love it so much.
I just got a new job and my first task was to create a site that will serve as a portal for looking up the statistics, bio-data and other information of residents in a certain state. The application that contains the information was designed by someone else. My job is to put it on the web and make it accessible for everyone. so how do i call external applications from within WordPress. Please help!!! i dont want to mess things up on my first assignment. thanks!!!