First things first,use a small screwdriver to loosen the screws

After you have done that,take out the screws and put them somewhere where you wont lose them

Now use something to pry open the back case of the laptop carefully.If you hear pops,dont worry,its normal.It may be difficult at first.

After you have pried open the case,remove it and put it somewhere safe where it wont bother you

Make sure your Laptop is turned off.You dont want to get electrocuted and/or cause problems to your laptop,do you?Also,make sure that nothing is in the ports of the laptop for safety reasons