no key required if it's standard set up.
a normal start would be
1, close the choke
2 tickle the carb until petrol is evident at the tickler.
3, kick engine over with clutch lever held in so the clutch rubs free,
4, kick the engine over easy to just draw some fuel in through the carb,
6 , kick over to come to compression then let the kickstart return to top and then a long swing with hardly any throttle should give you a bang in one or other cylinder.
make sure fresh fuel in the tank, make sure you have a spark (remove plugs connect ht lead to plug and rest against metal part of engine, kick it over and watch for a good blue spark on the plug) various carb settings need to be correct ( do you have a Haynes manual )