Press the green flag. For a tutorial about a much more complicated script, parkour (aka platforming), go here: http://scratch.mit.edu/projects/34429446/
Just a simple tutorial that I decided to make after realising that some scratchers need this information. If you use this, I would rather you give credit to me, @djpro, but you don't have to because I am sure that someone has done this before me. For a tutorial on platforming scripts, go here http://scratch.mit.edu/projects/34429446/