It does depend on the laptop. Most laptops have 2 ram slots and may have both already filled. In this case, to upgrade you will need 2 new sticks of ram. If there is only one ram stick in place, it is easy to add another.
Open the ram compartment and see whatyou have. Note the markings on the current ram and search in google.
Also, try this site: click here and fill in the details - this may tell you what ram will work for you