How to use oracle stored procedure using ado.net in dataaccess layer?

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ADO.NET

C#3.5

I have created stored procedure with input and output parameter in oracle
At Backend that is working fine when I tried to display at front end that stored procedure data is not fetching and not displaying in textbox.
I tried to resolve this by searching google and written exact logic but it is not displaying and not read the data.
SO could you please help me.

cmd.Parameters.Add("app_First_name", OracleDbType.Varchar2,50,). Direction
 = ParameterDirection.Output;
while (dataReader.Read())
                        {
                            txtUFirstName.Text = dataReader["app_First_name"].ToString();