Hi, I am new to web programming. Maybe there are already some protection library for security best practice that can i use?
The spectrum of security is wide. Can you please add more details?
Here is good starting point:
Is applying all of them is good if the library is exist?
I thought because i dont know about security, i just use all the library and follow the documentation
There is no library you just install to make your application secure. Security is a combination of discipline, libraries, know-how, maintenance and also time/money. So it depends on your specific requirements, web or app etc. and what the regulations are in your specific domain etc.
PS: Here you may find more Slim specific information and links about this topic: