Small Engines (Lawn Mowers, etc.): key start isnt working on briggs motor, power pac, lawnmower shop

Question
i just got a lawn king push mower given to me it has a key start and pull start ,i am trying to get the key start to work is there something like a power pac, or alternator that may need be replaced?or is there a charger pac missing if so where can i find parts?

Answer
there should be a battery that goes on it you should be able to pick one up at any lawnmower shop just look to see what size you need and that doesn't work check to make sure you got a good ground and that all the other wires are hooked up and one last thing if all that looks good very well may be a switch thanks let me know