up key =jumping animations down =crouching ect... its probably on here somewhere, i just couldnt find it ...!!!
aslo this site be interesting to people studying how to do walking animation ect
Develop games in your browser. Powerful, performant & highly capable.
In the How do I FAQ section "Animations":
et the animation according to a key pressed - LINK
In the beginner's tutorial "How to make a platform game" you can also find some explanation about mirroring and importing/setting animations frames.