Add expires headers or Cache-Control

Hi, I just want to ask I am not familiar with this to add “expires headers” or Cache-Control and I never used it before,.How can I add expires header to my css,js,img ?.I don’t know how to implement this to my code.

Thank you in advance.

in your webserver config, you can define such headers for certain types of files.

e.g. in Apache (if you have mod_expires enabled) you can set this in .htaccess (examples see linked page).