Clear the doubt

Hello,

SqlConnection cn=new SqlConnection("data source=COMPUTER-CBC14A\SQLEXPRESS;Initial catalog=siva");
cn.Open()
SqlCommand cmd=cn.CreateCommand();
cmd.CommandType=CommandType.Text;
cmd.CommandText="insert into siva1 values('+TextBox1.Text')";
cmd.ExecuteNonQuery();
cn.Close();
i got this error Unrecognized escape sequence