howto grub-install

[J.V.]

I have installed CentOS 6.0 on a SATA drive, default settings.

I was reading the grub manual and it led me to do the following:

At the root command prompt, I typed:
    #grub-install /dev/sda1

now when I boot, I have a black screen with a single blinking white cursor

Question 1)
    What went wrong?

Question 2)
    How do I get my OS back?

I have Windows 7 installed on the second SATA drive, how do I show this 
in the grub boot menu?
I read the manual section about "chainloader" and another section 
referring to "menuentry", but the instructions were not specific enough 
for use.

Question 3)
    What file do I edit to make "chainloader" go?  I understand the 
concept, so now what?

Question 4)
    Where/what file does "menuentry" go in?



J.V.