How to keep an iPhone app constantly running in the background?

I have a social network app that shows when I'm online and when I'm not on. How do I keep it running all the time so it shows that I'm always online? I know it will run the battery down but I just want to be able to have my profile viewable at all time.

Usually it should always keep u online as long as you don't double tap the home button whilst on the home screen and close it but it does kind of depend on what social networking site it was I just supposed you meant Facebook