just watch part 2 of scratch
part 1: https://scratch.mit.edu/projects/1367828709 part 2 : https://scratch.mit.edu/projects/1367898158 part 3 : https://scratch.mit.edu/projects/1368328985 part 4 : https://scratch.mit.edu/projects/1368615990 part 5 : https://scratch.mit.edu/projects/1369052676
