This question has had to be removed.
All of your constants have invalid names. You can't name a constant
According to the docs:
A valid constant name starts with a letter or underscore, followed by any number of letters, numbers, or underscores.
You'll need to rename your constants to have valid names:
define("DB_SERVER", "localhost"); // Host name define("DB_USER", "sec_user"); // Database Username define("DB_PASS", "eKcGZr59zAa2BEWU"); // Database Password define("DB_NAME", "secure_login"); // Database Name
Then you should be able to connect to your database:
$mysqli = new mysqli(DB_SERVER, DB_USER, DB_PASS, DB_NAME);