You can turn the flash off in modes other than manual, but you need to look in your user's manual to see how (I only know how on a Nikon). I would us A mode for this (aperture priority) so that you can control your aperture (f-stop) and open it wide, therefore blurring the xmas lights (is that what you want, btw? or do you want everything sharp?). Or, use manual mode like MK said.
Like MaryKay said, in this low light that you're probably working - the shutter speed is going to want/need to be veryyyyyyy slow
w/out a flash - so you're either going to have to use a tripod -or- a table or
something to stabilize the "shake" OR try increasing your ISO speed which just might do the trick and you might be able to still handhold. Using high ISOs in low light can be incredibly helpful and satisfying!
