How to Create a log file For Errors raises in Project

/// <summary>
/// Create a log entry in the database
/// </summary>
public LogEntry(string message, ErrorLogCause cause, DateTime when, object additionalInfo)
    {
    string excess = null;
    while (message.Length > 2048)
        {
        // Too big - truncate and add ellipsis
        excess = message.Substring(2048 - 3);
        message = message.Substring(0, 2048 - 3) + "...";
        if (additionalInfo == null)
            {
            // Great! We can save it anyway!
            additionalInfo = excess;
            excess = null;
            }
        }
    byte[] add = additionalInfo as byte[];
    AdditionalInfoType type = AdditionalInfoType.None;
    if (additionalInfo != null)
        {
        if (additionalInfo is string)
            {
            add = System.Text.Encoding.ASCII.GetBytes(additionalInfo as string);
            type = AdditionalInfoType.String;
            }
        else if (additionalInfo is byte[])
            {
            type = AdditionalInfoType.ByteArray;
            }
        else
            {
            new LogEntry("Unknown additionalInfo type supplied to LogEntry: " + additionalInfo.GetType().ToString(),
                         ErrorLogCause.ErrorInErrorReporting,
                         DateTime.Now,
                         message);
            type = AdditionalInfoType.Unknown;
            }
        }
    // Log the problem.
    string dbCon = ConfigurationManager.ConnectionStrings[dbConName].ConnectionString;
    try
        {
        using (SqlConnection con = new SqlConnection(dbCon))
            {
            con.Open();
            using (SqlCommand com = new SqlCommand("INSERT INTO SMAdmin.Log (message, loggedAt, cause, infoType, additionalInfo) " +
                                                   "VALUES (@M, @A, @C, @T, CAST(@I AS VARBINARY(MAX)))", con))
                {
                com.Parameters.AddWithValue("@M", message);
                com.Parameters.AddWithValue("@A", when);
                com.Parameters.AddWithValue("@C", cause);
                com.Parameters.AddWithValue("@T", type);
                if (add != null)
                    {
                    com.Parameters.AddWithValue("@I", add);
                    }
                else
                    {
                    com.Parameters.AddWithValue("@I", DBNull.Value);
                    }
                com.ExecuteNonQuery();
                }
            }
        }
    catch
        {
        // Anonymous catch: Error in error reporting system
        // Any attempt to record the problem will most likely makes things worse
        // as the whole system is to c**k anyway.
        }
    // Handle any extra info we couldn't fit in...
    if (excess != null)
        {
        // Problem: Issue as continuation error log and hope we can tie them together...
        new LogEntry("...Continuation...", ErrorLogCause.Continuation, DateTime.Now, excess);
        }
    }