Ah, I see.
create your event first.
A state transition use events. you can not create a state transition AND its event in one go.
1: go to the event tab, and add the event you want to use in a state transition
2: select your state, right click "Add Transition" and select the newly created event.
Does that help?
IF, when you right click on a state, you don't have a contextual menu with "add transition", then this is very odd indeed. Are you on mac or windows?
bye,
Jean