Your Trio has been designed to help you track your energy usage and meet the budgets you have set. 

If you pay monthly, then the best place to start is entering how much you pay for your electricity and gas, this information should be on your bill. 

If you do not have a bill to hand, but you do know how much pay in total to your utility, then just split that value in half, and use that for each fuel.  

You can always adjust it later.