Creating your own options-general.php page

You don’t. You would have to keep your new page in sync with the core file each time WordPress is updated … that would not be very pragmatic.
Hook into the do_settings_sections('general'); with register_setting() and add your code here.

There is a third parameter for register_setting(): you can register a callback function here which used before the value is saved to the database.

See the @Otto’s WordPress Settings API Tutorial for some examples. In one of my own plugins I do the same: Public Contact Data. See the method function add_contact_fields() for details.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)