I typed it into the documentation string box
nah, don't write out your scripts there. What goes there is a description of what the script does.
When you save it, it will be added to the magic effect. You then, right click on it, and chose
edit source. A new window will open. Well the compiler is the bottom white field. You know the rest.
Since this uses properties, you need to define where the destination will be. So, click the button
properties and a box will appear. (or you can right click and choose
Edit Properties). Select the property in that window, in this case destinationMarker, and then click on the button
Edit Value. Another box appears with a drop down. Cell, and the Cell reference. The reference is the destination that your script will send you to. The Cell is where this destination is held.
Im just covering everything just incase you missed something.
Edit: That script is correct. Just remove the {}