How to set up a conditinal formula w/letters vs numbers?

[lz]

I'm trying to create a conditional formula that will say true if the cell
contains a certain string of words and false if it doesn't.
For example:

If in cell A3 it says "yello" then true
If in cell A3 it says "black" then false
If in cell A3 it says "white" then false

However, it gives me an error message; is it because I can only use numbers?

 

[ozgrid.com]

Select A3 and use Custom; ="yellow"

 

[Dave]

Hi lz,
In the cell you would like your True/False answer, put:
=A3="yello"
This should produce the result you need.
Regards - Dave.