I'm not sure if there is a tutorial on this so I apologise if there is.
I got my character bouncing up and down correctly (idle animation)
If I press on the left arrow key I want my character to face left. How do I do this?
You would use the 'Set Mirrored' action.
I would very much recommend Ashley's - or one of the other - excellent tutorials from the Tutorial section at the top of this page. It will cover everything you need to get going on basic platforming and animation.
You can set event: When left key is pressed ==> Set (Character) width: (the negative of the current width size)
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Mirroring is easier than manually setting the width.
Best is Mirror all you do is set Keyboard keys or mouse key like below
keyboard left keydown = myobject mirror or Mouse button click = Myobject Mirror
myobject = notmirror
Or you can also use an idle animation when left or right arrow is not used
Try and learn from this demo I made for you