When you create an event, you have to double-click the Graphic box (the big empty box on the left side) and choose what character sprite to use. As Andar said, putting it into the folder only makes it available. You've still got to specify where to use it.
I suggest you hit F1 in the editor and take a look through the help file. This is really, REALLY basic stuff and you need to know it well. In fact, I'd suggest completely avoiding scripts (which require expert knowledge) until you learn the basics.