Hi,
ok, it's quite simple actually. when it says "none" in a field, it means it expects you to select a variable you have created on that fsm or a global variable.
so, in the playmaker inspector, select the "Variables" tab, and create a new variable of the type you want ( likely a vector3). then go back to the "State" view and your action, and then you can pick it by clicking on the "none" field.
If there is nothing listed there, it means you don't have any variable of the expected type available.
bye,
Jean