For the third time ... you use the built in data monitor to check what apps are using what amount of data or you do a Google search for other apps that do a more detailed job, install one of these and use it to check what apps use your data.
I can't really make it any clearer than that.
Hope this helps.
No need to be rude dude.... Some people Re more tech savvy than others. Maybe someone else can put up a step by step guide how to check.