Execute SP.

public struct NomAp
{
    public string Nombre;
    public string Apellido;
}

public Dictionary<NomAp, string> dicSelect(string connectionString)
{
    Dictionary<NomAp, string> dicResult = new Dictionary<NomAp, string>();
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        using (SqlCommand cmd = new SqlCommand("spSelect", conn) { CommandType = CommandType.StoredProcedure })
        {
            conn.Open();
            using(SqlDataReader reader = cmd.ExecuteReader())
            {
                while(reader.Read())
                {
                    string strNombre = reader.GetString(0);
                    string strApellido = reader.GetString(1);
                    string strMail = reader.GetString(2);

                    NomAp pair = new NomAp { Nombre = strNombre, Apellido = strApellido };
                    dicResult.Add(pair, strMail);
                }
            }
        }
    }
    return dicResult;
}


static void Main(string[] args)
{
    clsSQL sql = new clsSQL();
    string strEstado = "";

    try
    {
        strEstado = sql.isConnected(sql.strConn()) ? "CONECTADO" : "NO CONECTADO";

        Console.WriteLine("Estado de la conexión: {0}\n", strEstado);
        foreach (KeyValuePair<clsSQL.NomAp, string> kp in sql.dicSelect(sql.strConn()))
        {
            Console.WriteLine("Nombre: {0} {1} Mail: {2}", kp.Key.Nombre, kp.Key.Apellido, kp.Value);
        }
    }
    catch(SqlException ex)
    {
        Console.WriteLine("SQL Server Error: {0}", ex.Message);
    }
    Console.ReadLine();
}


CREATE PROC spSelect
AS
BEGIN
    SELECT TOP 5 p1.FirstName, p1.LastName, p2.EMailAddress
    FROM Person.Person p1, Person.EmailAddress p2
    WHERE p2.BusinessEntityID = p1.BusinessEntityID
END