I love how you drew marceline, but there is a little error I'd like to point out. her bite marks switch sides. You could've erased the bite marks when she turned, implying they stayed on the Left side of her neck. Just a little constructive criticism.
But Like I said, I like how you drew it, man. IT'S FREAKEH LIKE MAH LADY PYRAMID!
draw the pictures (or different frames whatever you want to call them) then go on [link] load the image then go down to where it says frame animation. Load the pictures in order then go down and select how fast you want it to go, press done or whatever it says then save the picture as a gif file.