Sample Size

First of all, Hello.
I'm newbie on this forum. I need a help with my research method subject regarding the sample size that seems a bit complicated for me. Thus, even a little help will be appreciated.

Here is the problem.
I've got a exact quantities of the population, precisely, employees. So I need to find out the exact sample size which will be proper count to do sampling on.
I've made an screenshot, so not to type all the information on here.

http://i.imgur.com/9nbTuwO.png

I'm not asking you to write this for me, but a little bit help with the right directions will be more than appreciated.