How do i make sideway walking animation?

So im making a game and i need help to make like If player is walking using D or A i need to play a animation that makes his legs walks to his direction, But i dont know how to do this like how some games make i tried using an code to detect if A or D is pressing then play the anim But it just plays on the air, i tried stopping the animation when on air but when you get on ground again you wont play the animation i need help

This may not be the best answer, but I can try to help. Go to roblox studio,try going to plugins, and get a build rig. Then select the dummy and get an animation editor. From there, you should be able make an animation to put on your player. Sorry for the terrible answer. I can help more if you got the animation done.