Now let me tell you what F1,F2,F3 yml files are. actually these are frames for animations so in F1.yml you move the right leg forward and move the left leg back. and then in the F2.yml file, on the contrary, you move the right leg back and left leg forward, and finally in the F3.yml file, you move it to its original position and you finish the animation. of course you can add more frames F1,F2,F3,F4,F5,F6... this way you can add infinite frames. but I add at least 3 frames and the animations are flawless.