javascript and forms help (oncheck)

how do I get javascript to pickup when a checkbox has been checked
and then update a set text input with a value


eg
[X] I dislike the color Red
[ ] I dislike the color Blue
[ ] I dislike the color Green
[X] I dislike the color Yellow

I dislike these colors "Red,Yellow"

thanks for any and all help

onclick

Eric

...or onchange...