Bokeh is the photography term referring to the way in which the lens renders out-of-focus points of light. Want to make your own?? Read on.
You'll want to create a very deep field of depth to get your best photo so set your camera to aperture priority mode ("Av" if you have a Canon like me and "A" if you have a Nikon).
Then, set the aperture at the widest that your lens will allow (1.4 or 2.8 is best) to capture the most light. In this setting, your camera will set your ISO and shutter speed automatically for you depending on the lighting conditions in the room.
Next, take your object - your favorite ornament, your dog, your baby, a christmas card, those santa cupcakes you spent a couple hours slaving over, whatever - and place it a few feet in front of the lighting that you plan to blur. Set your camera to manual focus (MF switch on the lens) so that you can make sure that your intended object is perfectly in focus and snap away!
If you want to do something more abstract, you can set your camera to manual focus and capture just the lights themselves! I took the one below of my Christmas tree before we put the ornaments on. It would make a great series of framed prints for holiday decorating!