Connection String Problem Oracle .Net

I am new to oracle and am trying to simply connect to an oracle db, but I am not sure where to find the proper credentials to put in the connection string. I simply downloaded and install oracle express edition on my machine, then installed the .Net references. My simple code is here:

 string oradb = "Data Source=XE;User Id=hr;Passw开发者_如何学Cord=hr;";
            OracleConnection conn = new OracleConnection(oradb); // C#
            try
            {
                conn.Open();
                string sql = "SELECT FIRST_NAME FROM EMPLOYEES WHERE EMAIL='SKING'"; // C#
                OracleCommand cmd = new OracleCommand(sql, conn);
                cmd.CommandType = CommandType.Text;

                OracleDataReader dr = cmd.ExecuteReader(); // C#
                dr.Read();

                //label1.Text = dr["dname"].ToString(); // C# retrieve by column name
                label1.Text = dr.GetString(0).ToString();  // return a .NET data type
                //label1.Text = dr.GetOracleString(0).ToString();  // return an Oracle data type
            }
            catch (OracleException ex)
            {
                label1.Text = ex.Message;
            }
            finally
            {
                conn.Close();
            }

I am getting a TNS:could not resolve the connect identifier specified exception. Its probably because my connection string is wrong is what I am guessing. I cannot even go to the Server Explorer dialog in Visual Studio and test a connection correctly to my oracle db.

What steps do I need to take to figure out the proper credentials to plug into my connection string? Or wording it like this.... If you were going to install oracle express on your machine, then connect to a .Net app what steps would you take to set up the connection string?

Maybe it is looking for a data source defined in a tnsnames.ora file called XE.

Try the Easy Connect naming method in the Express edition. It enables application clients to connect to a database without using any configuration files, simply by specifying the data source attribute through syntax shown below:

user id=hr;password=hr;data source=hr-server
user id=hr;password=hr;data source=hr-server:1521
user id=hr;password=hr;data source=hr-server:1521/XE

Replace hr-server with the dns name or ip of your machine.