Hi guys , i just got a cam......i am very newbie in this.....hope someone can enligten me......

mi cam max 4 secs shutter.....to 1/1000 (i can never seem to get a focus using 1/250 or above leh......using auto focus)

the aperture size is f2.4 to f9.6 ......

how do i know when to use AP or SP?
which one is better??

heh , thanks for any replies , hope can learn more