How to display user input in a label or textbox after submit

Hello I'm using Expression Web4 (They told me to come to this forum) and trying to display user data as follows:
After user inputs first Name that is submitted to the SQL database (the records are being added fine) I want to display the users name saying the following. 
Michael was added to the database successfully. so I have the following code for onclick event
{
FirstName.Text = inputForm.FindControl("firstNameTextBox").Text;
}
I must use expression web and I use the find control method because the textbox is in a form view. The above code gives me the error
CS1061: System.Web.UI.Control does not contain a definition for 'Text' and no extension method 'Text accepting a first argument of type 'System.Web.UI.Control' could be found.......
My back up plan is to do a hidden label Label1.Visible = true; on click with "The student was added successfully" But I wanted to add the firstName too.
The control is &l ...