i have a sign up form in php, when someone signs in they get redirected to mysite.com/xyz/ but i want when people visit mysite.com/xyz/subdirectory/ they are asked to enter their login details before they can enter into the page.
How are you checking to see if they are a valid user?
The easiet and most effective way is to use a server cookie. Then you can check to see if they are a valid user on each page that you want protected by using the cookie, a tutorial discussing this can be found below.