PHP, MySQl

I also asked you where you are stuck ;-) Writing select queries, updating tables, ... Or with the design of the tables?

OK, so a user is logged in. This means that somewhere you have a database table that stores the user's credentials.

First thing you need is a session variable that stores an unique identifier for that user. so your table with the user credentials needs to be something like

PK_userID (autoincrement; gives unique identifier)
Username
Userpassword
...
...

This article gives some examples with session variables in PHP: http://www.w3schools.com/php/php_sessions.asp

The session variable will tell you that a user is logged in (useful if he/she goes to another page on your side so he/she does not have to login again) and can be used to refer to records belonging to that user in tables.

That should give you a first step.

For more help, you need to provide the structure of the tables that store the user information. Are those additional fields that you're talking about in the same table that stores the user credentials or in one or more other tables.

I will not be able to help you much with the PHP side of things as my knowledge is very rusty; last time I did PHP was over 6 years ago.

Your question is not clear (to me). Do you want to remember the user credentials that are used for login? You can do so using session variables.

If this is a panel where the user can update his/her details and you want to store it in the database, you can execute a stored procedure or query (both using parameters and both doing an update of the table). In that case you have to remember the user ID at the moment that the user logs in.

So which one is it? And where are you stuck?