How to integrate multiple users into a single user microblogging site?

I am very new to PHP and found a tutorial on how to build a Twitter-like microblogging site from scratch. It works great, except I have no clue how to integrate a place where other uses can sign up and use the site? It seems like it is only set up for one user.

Tutorial I used

Any suggestions?


So continue reading and you will be welcome when you have a more specific question:

This is a good tutorial using PHP5 and PDO (like @Charles recommend). Avoid reading some old tutorials (IBM is a good source, but the tutorial is 3,8 years old).


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