Nah, you can do it all automatically in the calculator. I presume your calculator has similar buttons to mine which is a Fx-85WA. Anyway.
Press the mode button, then 2 (SD) to enter SD mode.
To make sure there's nothing in the memory already, press shift and then AC (Although on yours it looks like it might be shift and mode). Press equals to clear the memory.
Now add numbers one at a time by pressing the number, followed by M+
When you're done adding numbers in, you can choose one of the options that should be printed on the card that's on the inside of the calculator case. On mine, you press
Alpha then A for the Sum (x^2)
Alpha then B for the Sum x
Alpha then C for n
etc
For SD it's shift then 2 (looks like xQn)
All this should be on the reference card for the calculator. Dunno what functions your calculator has though. Should be able to do it. Mine does stuff way more complicated than that, so I would have thought you'd need a pretty crap calculator to not do SD :)