I have finished PHP & MySQL: Novice to Ninja and it was the most best php book for beginner..I would like you to recommened me the next step or book to read or online tutorials.
I'm glad you found it useful! There are a few suggestions for where to go next at the end of the book.
Now that you're familiar with objects and classses I'd recommend looking at the following:
Unit Testing - https://www.sitepoint.com/re-introducing-phpunit-getting-started-tdd-php/
Package management with composer - https://www.sitepoint.com/re-introducing-composer/
Version control - https://www.sitepoint.com/git-for-beginners/
You might also want to start looking into PHP frameworks like Laravel and Symfony. Most of the concepts used by the popular frameworks are covered in the book, though each framework does it differently.
Maybe not the immediate next book, but one you should read:
Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides: Design Patterns. Elements of Reusable Object-Oriented Software. Addison-Wesley, 1995, ISBN 0-201-63361-2