i am using this method.
add a from that you want to pop up, add all controls you need. in the code you can handle the user input and return result to the caller. for pop up the form just create a new instance of the form and show method.
/* create new form instance. i am overriding constructor to allow the caller form to set the form header */
var t = new TextPrompt("Insert your message and click Send button");
// pop up the form
t.Show();
if (t.DialogResult == System.Windows.Forms.DialogResult.OK)
{
MessageBox.Show("RTP", "Message sent to user");
}