Hi,
We usually use (almost everybody use) 2-set seyboard.
2-set keyboard is so called "QWERTY" set (the keys in the upper left side on your keyboard).
3-set keyboard is called "DVORAK" set and now almost nobody use it.
Especially in Korea, 3-set keyboard was initially intruduced for the typing efficiency, but people were already so used to the 2-set key and the policy failed.
Just use 2-set, and don't use 3-set!