Insert Values From 2 Different Sources

Hi,
I have a button that that executes insertion of data into a database.
For the data it inserts into one column, the data is located in another database table.

As well as this being inserted, I would like more data to be inserted in the same column, which comes from textboxes which are located on the same page as the button that executes the insertion..
For example: someone types in information into textboxes, then presses the button. The code behind then inserts the data from the textboxes plus the data from the other table (for which the coding is already done).
Here is my current code:
 
    public bool [snip](int ProductId)
    {

[snip]

        command.CommandText = "INSERT INTO Messages (sendername,recievername,message,senddate,subject) VALUES (@sendername,@recievername,@message,@date,@subject)";
        command.Parameters.AddWithValue("@sendername", System.Web.HttpContext.Current.User.Identity.Name);
        DataView dv = SqlDataSource2.Select(DataSourceSelectArguments.Empty) as DataView;
        string receivername = " " + dv[0]["Usersname"].ToString() + " ";
        command.Parameters.AddWithValue("@recievername", receivername);

        DataView dv2 = SqlDataSource3.Select(DataSourceSelectArguments.Empty) as DataView;
        string message = dv2[0]["paymentinstructions"].ToString();
        command.Parameters.AddWithValue("@message", message);
        command.Parameters.AddWithValue("@subject", TextBox1.Text);
        command.Parameters.AddWithValue("@date", DateTime.Now);
        command.ExecuteNonQuery();

        con.Close();
        command.Dispose();
        return true;
    }

 
So along with "paymentinstructions" being inserted into 'message', I would also like the values from TextBox4, TextBox5 and TextBox6 to be inserted... It would also be good if text could be inserted infront of the values of these textboxes - e.g.    Price: "TextBox4's value"

Does anyone have any ideas? Reply if it needs further explanation.

Thanks,
Jon