Know that this project is a duty that I had to carry out for my school. I created it in 2 hours and it is therefore normal that it contains bugs. Anyway... press the right and left arrows to move Mario and the Space barr (or up arrow) to jump.
Thanks to @ImScratchPoxTV for the ideas, to Google for the pictures, to @BirdNani for the music on his project "New Super Mario Bros. Scratch (DEMO)" and to Edsal Fr (On YouTube) for the platforming script.