With focus pulling you employ manual focus and long exposures. A good tripod is a necessity! The fireworks were 5s exposures, the Christmas tree 8 seconds.
With fireworks I think the images are best if you start out of focus and slowly rack back to in focus. With my Christmas tree I was also zooming the lens while I was racking focus to make the light trails change in size.
Get out there and give it a try!
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