please if I may ask seeing the way comments and posts are being made you will find out that post are being displayed to people in a particular country like someone from Chile cannot see the posts of another person from Russia, or posts can only be shown to friends or mutual friends.
Please how can I use php to do that on my comment system

If a user wants to go to profile.php and I assumed that the user is not logged in.
Now i want to redirect the user to login.php and in the login.php will now echo something like YOU MUST LOGIN TO VIEW THIS PAGE and after the user loged in will take the user to the profile.php which the user requested

How will i do that stuff and and also after echoing YOU MUST LOGIN TO VIEW THIS PAGE I will want the echoed content to disappear...

how to allow users have their own pages by filling out forms like page title, background color,image,log o e.t.c this will be like Facebook style page