Adding more RAM to MacBook Pro Help!

Dear Apple Support Community,

Ok so first of all don't tell me to go search for older discussions >:(

Here are my system specs:

MacBook Pro 15", Mid 2010

Processor - 2.66 GHz Intel Core i7

Memory - 4GB 1067 MHz DDR3

Graphics - NVIDIA GeForce GT 330M 512 MB

Software - OS X 10.8.5 Mountain Lion

I was going to buy some extra RAM and boost up my computer to about 16 GB total because my computer is running a bit sluggish lately when I'm running several apps at once (such as pages, keynote, chrome, steam, itunes...) but now that I've seen a few videos online and some reviews on amazon, I'm not completely sure which RAM is the one that will not screw up my computer. I saw a video on 'UnboxTherapy's Channel' where he said something about the timing of the RAM which is in the format like 9-9-9-24 or something, as well as some review saying something about the computer not working at all thanks to the RAM because the computers didn't match..

Please help me find a 16GB RAM that will work on my computer (please try and keep the websites amazon if possible, I live in japan :/)

and please explain to me what the RAM timings mean and how to figure out my timing...

Thank you for reading 😀