The RAM stands for Random access memory, which is what stores all of the computers and users files. It is attached to the mother board via a slot, of which one might be filled in. Think of the RAM as a workbench as the RAM is essentialy where programs are sent to be run. There are different types of RAM, such as DDR, DDR2,DDR3, EDO, FPM, SDRAM, SODIMM and RAMBUS. You will need to find out what type of RAM the computer takes. To remove the RAM, simply press down on the tabs at the end of the slot and the RAM will simply pop out. To insert the RAM, align the RAM along the slot with the gap above the gap in the slot, then gently press down on one side until the tab on the side goes up, locking that side of the RAM in place, repeat this for the other side.
When you need to replace or add onto the RAM, make sure that are enough RAM slots available and also do not add too much as it can slow the computer down.