hi there, i m the newbie in asp.net. it is totally different frm the asp language that i can manage it. i try to use the Validator Callout Extender from the asp.net ajax site. i have no idea on how to change the popup validator CSS.
can some expert guide me more? guide me steps by steps. i have do some research on the google. but i still not understand how it works. plz help..thank you.

Go to the directory where you installed theAjaxToolkit, in my case C:\AjaxToolkit\SampleWebSite.

Go the SampleWebSite directory. Find the StyleSheet.css file. Look for "callout" and start from there.

Also read the readme text.

AspNetGuy....

my dear friend i thing this solution will rectify your problem
Go to the directory where you installed theAjaxToolkit, in my case C:\AjaxToolkit\SampleWebSite.

Go the SampleWebSite directory. Find the StyleSheet.css file. Look for "callout" and start from there.

also for further clarification see this link
http://codesforprogrammers.blogspot.com/