How we can open Ajax modal window depends on condition

Step one Copy paste this code in html part.

make sure that css path will find.
css is as folows
.modalBackground
{
background-color:Gray;
filter:alpha(opacity=70);
opacity:0.7;
}

	Account Registration
	The Site is not intended for or directed to persons under the age of 13. Because, if you register for an account with us, you represent to us. that's why you are 13 years of age or older. (Dummy Text)*

Step 2) now on code behind

if (true)
{
ModalPopupExtender1.Show();
}
else
{

}

here one thing more if u wana always call modal window the set lable id of its

Behaviour id .

Mahesh K. Sharma.
E-mail me
mahesh.sharma@live.in