I have 3 textboxes in my webform.I want my user to enter valid entries into them. If user leaves any textbox empty.I want Give him an alert to him (like a msgbox in vb.net).I'm using textboxes in asp.net(web server controls).I dont want to use the validation controls as they wont give a pop up message.

in the submit button do something like

if (txtField1.Text = "")
{
msgbox = "Sorry please enter something in txtFeild1";
}

Try something like that.