Get reference of this link to get OnCLick tooltip on textbox.
http://jquerytools.org/demos/tooltip/index.html.
FYI: oliver you also need to do some exerciser on it like following logic will work.
#1 :- take a
div(Display:None)
with the text whatever you want to show on click of textbox.
#2 :-
onclick of textbox
you need to apply the CSS class on div for tooptip.
TRY HOPE IT WILL HELP