colorful textbox

I am creating a lexical analyzer for my school project. Does anybody
know how to change the color of fonts in a textbox according to every
single word.

Example, all words typed in a textbox that start with letter "A" would
have a font color of blue and all items not starting with letter "A"
would be colored green.

I would deeply appricate any form of help that can be extended to me.

tnx a lot guys especially Tami Selvil for having tried to assist me
before.