I agree with Anex, am doing contract work as an IT technician at the moment and offer local IT support in the evenings and I have never broken a memory module (and rarely unplug the PC)
Only thing that is a good idea is to take off your watch as that can damage components sometime.
Dell's are very easy (its what we have at work), should have two quick release buttons at the back of the case (on the sides).
Push these in and lift and the case will hinge like a bonnet.
The memory will be towards the front on the case and it should have two slots, if you are removing the old one, push the two little white plastic clips down and away from the memory which will lift the old module.
Then carefully lift it out holding the two corners and put it to one side.
Take the new module, again holding it at the edges and place it in the slot. Then to save your fingers, take the piece of paper that comes with the memory and push down on the memory with the paper between the memory and your fingers until you hear a click, this is the plastic clips moving into place.
Hope this helps
Andrew