By now i am sure you have seen it, here is how to do it. Head over to the Star Wars Facebook Page Here. Once there click on the “Try It” Button.
You will get a pop-up window will open with the blue lightsaber shown, here you can change and set your settings. You will have the option for either the blue, or the new 3 bladed red. (Top Center ish)
You can set the length of time you want your profile image changed. ( Bottom right) You can also change your profile pic itself. (Bottom Left)
You can also change to other things like sports if you prefer.(Top Center ish)