How Do I Store An XmlDocument In SQL Server 2005

Hi,
I have  xmldocument type that stores xml data. I would like to able to store that data in sql server 2005 as a xml data type. How can I accomplish this using ado sqlcommand?
 XmlDocument xdoc = new XmlDocument();
SqlConnection conn = new SqlConnection(System.Web.Configuration.WebConfigurationManager.ConnectionStrings["Test"].ConnectionString);
conn.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "spStoreApp";
cmd.Parameters.AddWithValue("@PersId", "222-22-2222");
cmd.Parameters.AddWithValue("@AppData", xdoc);
try
{
cmd.ExecuteNonQuery();
Response.Write("Storage of application successful");
}
catch (SqlException sqlx)
{
Response.Write(sqlx.Message);
}
conn.Close();
thanks in advance.