code for password validation for new password,confirm passd.

Hi,
write a Stored procedure which have two condition first match the old password and another if matched then update new password.password does not matched must have return using out parameter

if (txt_fullname.Text == "")
                {
                    MessageBox.Show("Please Enter the full name of the user");
                    txt_fullname.Focus();
                }
                else if (txt_loginname.Text == "")
                {
                    MessageBox.Show("Please enter the login name");
                    txt_loginname.Focus();
                }
                else if (txt_pass.Text == "")
                {
                    MessageBox.Show("please enter the password");
                    txt_pass.Focus();
                }
esle
{
        insert_data();
}