This is essentially the same as the post you deleted.
In the first place, it is not polite to delete a post that has been replied to – it makes the reply incomprehensible to others reading it. (I have removed that thread)
In the second place, you shouldn’t start a new thread about the same question.
The following corresponds exactly to the instructions mbaney gave in the now deleted thread:
Select cell F3 (the cell to be formatted)
Select Format | Conditional Formatting…
Select Formula Is in the first box, and enet =(A3=1) in the second box.
Click Format…
Activate the Patterns tab
Specify the color you want.
Click OK twice.