You don't mention which Nokia unit you have, but I suspect that you are trying to open it the right way and are struggling.
I have a Nokia 3310 and it is very difficult to open it. You have to be brave and push the button down hard with your nail as you try to slide the back cover upwards towards the top of the unit.
To download photos (to your computer) you have to connect your mobile to your PC. I have used a UK2 cable and also a BlueTooth wireless connection. Both work well. The cable is more reliable and cheaper. Find out which cable will fit your mobile phone. They will all come with a USB plug at the other end to go into a free USB port on your PC.
(You could also use a card reader to read the photos directly off the memory card which your phone uses. I have found this the best way to move large files between my PC and phone, but it does mean getting the back off your phone every time you want to do this.)
Shop around for the cable. Nokia charge £32 for the one I needed. I picked it up via another company for £8!
D Harry, November 2005