change color of certian words in a text

["吕晋鹏" <sssssiqn gmail com>]

i want to change the color of certian words in a text,for example:
when you input some word in a text ,then certain words are changed color.
"if i were a bird ,then i can fly",when i input the sentence ,then word "if"
and word "then" change color(from black to red),but other words still keep
original color,how can i do it?
thank you!
regards