What does the validate method to do your form?

What does the validate method to do your form?


Is there any place that lists simple things like "IF you run the
validate() function on your form and it finds errors, it makes the
following changes to your form..."
For example it adds the error class to your input field and to it's
label. I have been reading the docs for days and can't find simple
explanations of this sort.
I finally found a sample at http://lab.distilldesign.com/jquery-form-validation/extending/
that at least gave me an understandable example where I finally
figured out how the function was styling things. At least some things
anyway.
Another question and more urgent right now is this :
How do I get rid of the text "This field is required." that is placed
after my input field? I don't want it. I just want to color the
background of my input field.
Thanks,
Chris