php project question

my question is how directory use in php project? which means by creatin folder example i want to do eyecare management project in hospital there five actor are there,admin,data clerk,ophthamologist,opthometrist and ophthalmic nurse. for those i create 5 folder for php and i want to use one login page for all by using role but when i use login page out of folder its not do and when i use in folder its not interconnect to each other why?