Then you have power to the ECU. Now we move on to the (sorry to say) harder stuff. The procedure and system the car uses to activate the starter is complex, if the ECU is missing something it expects or knows of an issue it often wont engage the starter.

Turn on parking lights
Disconnect battery, wait 15 seconds
reconnect battery (going to be a spark, dont let that bother you)
Try it, if yoiu get starter engagement but no start, keep trying. If, after three tries, you get nothing again, we can work on a SKREEM issue. If you get nothing at all, we've got to reallly get into this