Take the gas cap off and prime the carb and see if it will start up and run eventually (usually the third or fourth time it starts and then stalls will allow it to actually run). If not then put gas in the tank and see what happens.

When I prime the carb I like to use a top from an aerosol can, spraypaint, shaving cream, hairspray or a small plastic cup. I just do that because sometimes you will pour it out of a can and make a real mess of everything. Pour it in the primaries and hold the pedal to the floor and crank it till it fires. When it fires let off and just try to keep it running by blipping the throttle. Repeat until it will stay running by itself.