+ ToyGirl: Angle Equal to 0
+ ToyGirl: ToyGirl overlaps Block
-> Block: Set horizontal speed to 205
+ ToyGirl: Angle Equal to 180
+ ToyGirl: ToyGirl overlaps Block
-> Block: Set horizontal speed to -205
That will pick that instance, and move it.
Pick by closest is best used when you don't have a usable collision.
Now if you want that to only happen when key x is down simply add a mouse&keyboard event:
+Key "x" is down
+ ToyGirl: Angle Equal to 0
+ ToyGirl: ToyGirl overlaps Block
-> Block: Set horizontal speed to 205
And then if you only want that to happen when she's not on top of the block:
+ MouseKeyboard: Key X is down
+ ToyGirl: ToyGirl overlaps Block
+ ToyGirl: Angle Equal to 0
+ ToyGirl: Y Greater or equal Block.Y
-> Block: Set horizontal speed to 205