Sniper123,
It's very highly doubtful you will be able to use an admin back-end from ANY other application!
An admin back-end is basically a special application which allows you, the administrator to make changes and updates as appropriate.
If the game is based on PHP, there is a very good chance it backs on to MySQL, or some other database (most commonly MySQL when its PHP).
In order to develop a back-end, you or someone would have to take a look across ALL of the code that the game uses, in order to add correct functionality.
Dependent on the size and complexity of the game, this may be a daunting task.
If you can relate this game to the popular facebook variants, if this is on a lower scale - as I would imagine it is... you could just use PHPMyAdmin, however you would have to learn what values in the MySQL table do what.
What I would recommend is this: (Again - assuming the game is PHP based)
1) Install the game on a TEST server
2) Create accounts /play game / add values, etc
3) Install PHPMyAdmin** Note: Your web host may already have this installed for you.
4) Go into PHPMyAdmin, and look at the table that was created - during the installation of the game it may have asked you for a database, when you look into this DB, you may see a series of tables.
Most programmers will develop the table / field names to make sense, i.e. a table called users will have user, password, email, first name, etc etc in the database, making it relatively obvious what each of the fields is for.
5) Make some changes, look for things such as Level, Mob Size (dependant) weapons or whatnot, and attempt to play with the values.
Once you go back into the game you will see exactly what these things do.
I would start with this, once you get a handle on how the game works, you can work on it with phpMyAdmin then you can develop an administrative back-end.
If you are new, you will need to familiarize yourself with QUITE a few topics.
I would recommend starting with that, then once you have a little more knowledge on how the game works on the back-end, take a look at the tutorials found on this site, as well as google, and build yourself a foundation of PHP and MySQL.
We can help you with specific topics, but to be completely honest I don't believe anyone will build such a complex system for free / via public boards.
If you can't do it yourself in a timely manor, I would recommend paying for a service, via internet.com's freelancer site. I am sure you can find someone who can do it for a reasonable fare.
