Converting Sprite Sheet into a .anim file

I'm using the RobotBoy asset provided by unity. I want to make a new animation so I modify the RobotBoyIdle sprite sheet to include a hat and save it as a new spritesheet. Now I need that sprite sheet to be converted into a .anim so it will work with the Animator state machine. I read through documentation and could not find a clear answer on this. Thanks in advance for any help!

 

Hey, I know that this was ages ago but I'm trying to do the same thing and saw that you had no reply and I just figured it out. The key is to when you modify the spritesheet in Assets\Standard Assets\2D\Sprites, don't save it as a new one, save it over the original, and voila run the game and as if by magic it will be the new modified animation.