How to change text to color every time you write it, like in the post, please read.

Hi, Iv haven't been programming for months, because I had computer problems, so now I have a new computer aging but any was, My question is.

I have a notepad that I have made and I need some text that you type and the color changes.

Like
If you type the word (the) It makes the color blue every time you type (the) and its blue.
And the same with (is) but with the color red.

I just need a little example, Please I don't want you to write it for me just explain.

Thanks:)