It seems to me that your method would set angle to 90? everytime you hit S. What happens when you hit S repeatedly? It's really a simple thing to do, all you have to do is look. I'll give you a step-by-step when I get home tonight, but just take a look through all the actions anyways to get yourself more familiar with the engine. It will really help you out a lot. Also try using all the actions to see what they do and you should be able to come up with solutions to problems much more complex than this :)
Okay here is what you have to do:
Create a new event -> Keyboard -> On key pressed -> Where it says <click to choose> click it -> Press W -> Press OK -> Press Done
Create an action -> On the very top it says 8Direction, click Simulate control which is in that section -> Where it says control, choose Up.
Voila you now have W control your Up arrow movement. Do that with the rest of the keys and you should be set. I hope this helps you.