Question about burning gas

Dangerous Experiment in the wrong hands
What you want to do is not especially hard, but requires the right equipment. I'm worried that you will blow yourself up if you try and wing it with stuff laying around the house. The basic technique is to react a known amount of methane and oxygen in chamber that is surrounded by water. The container for the water is well insulated so the temperature rise in the water represents the energy released in the reaction. Here is a link with more information. A local college lab will have what you need. Maybe you should try there.