I got a question about dark energy

Hey
I have a project about dark energy. Part of it is that I need to make some kind of homework problem with this topic. The article talked about using 1a supernova data to see the expansion of the universe. I was I would first calculate the luminosity or whatever they did. Than using that data with the modify the Friedmann equation, finding the cosmological constant. I dont think the supernova data would fit. I was skimming over the chapter and saw alot of formulas so maybe i can derive some of the formulas or somthing. Well any advise or suggestions let me know thanks.