I don't know that I can offer much more than Aldo recommended. My method of learning is to just jump in and do it. php.net will be your biggest go-to reference. StackOverflow will be your friend.
You'll probably want a good IDE that supports PHP. There's plenty of discussions about that and everyone has their favorite.
As for frameworks, I don't think I can offer much advice. Everyone is different as to what style they like. Laravel seems to the be most popular at the moment. But there's plenty others: CodeIgniter, CakePHP, Yii, Phalcon etc., and they all do a fairly decent job once you get them up and running. It's a matter of preference. You might check job listings in your area to see what technologies within the PHP ecosystem are most sought after and focus on those.