sd 630

Hello everyone!

I am a new owner of the powershot sd 630. This is the first time I ever bought a Canon camera (cybershot used to be my preferred choice) so I am not very accustomed to it. Just today I took pictures of fireworks (with the fireworks mode)--well, they turned out pretty crappy. They are pretty much a mess of bright lines of all colours. Had I not been there, I would not be able to conclude that those are indeed fireworks.
Also, the other day, I wanted to take some pictures of Toronto's skyline at night. The camera did not "catch" enough light so the pictures truned out pretty dark. I did use the nightsnap mode.
If anybody could point me into the right direction, that would be very appreciated. Needless to say, I am not very good with cameras, so please use simple language.

For fireworks use a longer shutter time (5-15sec.) and set the aperture to the highest (F8 or whatever it is) and ISO 100 or 80. You will be using a tripod.
Same for the nightscapes.
Keep the ISO as low as possible, as to avoid grain.
To be able to set aperture, ISO and shutter time you must enter some sort of Manual Mode. You read in the instructions for that.

i didn't know that shutter speed and aperture can be manipulated on the SD630! hmmmmmmmmmmmmmmm?

thanx.
will try to do just that.