I apologise if this is a stupid question, but my roots lie in PHP, and not Javascript. If anyone can help me I'd be very grateful.

I have a form for a user to submit, but I would like to have either:

a) a checkbox that, when ticked, "greys out" certain text fields so that they can't be edited

b) a button that will reveal/hide a part of the form

If possible, I would like to do either of these WITHOUT refreshing the page.

Any ideas (and bear in mind I'm a Javascript newb)?