Hi
Congratulations on your purchase.
The back cover should be secured by four screws. On my S1080 they are hex screws so I am assuming that yours will be the same. Once this cover is off you will be able to see everything that is in the unit and replaced as needed.
The specification on the S1082 is DDR3, but there is only 1 slot so when you remove the DIMM that is there, just replace it with the same type and speed, just a higher capacity. Be careful not to buy DDR3L, which is low voltage DDR3 as this may not work. If you like, you can post the partnumber on the memory when you remove it and we can tell you what is available on the market that you can buy.
Replacing it is very easy. Just pull the clips at the sides holding it and it will pop out. Line up the new one in the slot and press it down until it snaps in. Done.