Php Admin Section with Multiple Users

[AdmanX]

Hello,

I am currently building a site for friends that would like to have 1 site but have 4 separate blogs on it.

I have created a basic php admin section which allows 1 user to go in and add posts, manage posts and delete posts.

What i would like to do is change this so each user can log in and are presented with their own section of post / manage / delete dependent on the username they use to log in so that either one cannot affect the others.

If anyone can shed any light on this that would be a huge help.

thanks,

[AdmanX]

I hadn't added the code i have used so far as it was a basic tutorial i followed via a dreamweaver tutorial and am very open to starting fresh