Mmn, doing it by events might be a little tricky for a beginning eventer, but it's the best way to do it.
Just make a picture in Paint.NET or another image editing program that is 1280 x 960 and make it completely black. Then use a gradient tool or whatever is appropriate in your image editor. and make a circle with origin in the centre of the picture (640, 480). For a three tile radius, you're looking at a circle with radius 96.
Once you have that picture, then the eventing is easy. Just make a parallel process common event that acts on a switch. You can choose the switch, and whenever you want to turn on the lamp or whatever, then just turn that switch on.
In any case, inside the event, just make it look like this:
@>Control Variables: [XXX: Screen X] = Player's Screen X
@>Control Variables: [YYY: Screen Y] = Player's Screen Y
@>Show Picture: 1, 'Picture', Center (Variable[XXX][YYY]), (100%, 100%), 255, Normal
@>Wait: 1 frame(s)
I've attached a sample picture.