changing cell color by word

I don't know much about excel and how things work but I am trying to learn. I am making an excel document for my job and was wondering if I can have it so that when someone types a certain word the cell would change to red or something like that.

depends of which version of excel you have! up until excel2007 you could use conditional format for 3 different criteria
say you want yes=green,no=red,maybe=orange
then select cell goto format/conditional formatting
choose cell value is equal to option and type in yes
then click format button
then click patterns tab
choose colour green
click ok
now when yes is inserted in cell it will change green
you can then use 'add 'to do the two others
there is an addin that will let you do up to 30 conditions but i cant remember where it is but someone else will probably post it here.
in excel 2007 things change but i dont use that so again someone else will probably post it here.

Thank you for your help. I forgot to mention that I am using excel 2003. Everything worked great. Is there away for me to say put yes in cell B1 and have cell A1 change colors?

to reference another cell use the 'formula is' option instead of "cell value is"
then in a1 put

=B1="yes"
and select colour ect