I have a 2000 Oldsmoble Intrgue put a new battery in and I thik the anti theft has shut down the car.

What do you mean it won't work? Explain.

The security, antitheft or lock picture/icon is a visual indication that something in the car's antitheft system is failing. In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterprets this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. This link explains it pretty well.
http://www.diy-gm-security.com/

Have to work from the top or bottom & possibly thru the fender

Try a You Tube Video to see if there is something to watch

When folks ask questions like, that I assume your experience
& skill level is next to nil

If you could disable it, they wouldn't call it anti-theft.

you need to use your key fob to reset the anti theft system you should be able to find the procedure in your owners manual under battery replacement.

1st of all Read Your owners Manual, Depending on the Radio you have in it will depend on the Alarm system . Also Completely Disconnecting the Battery Will Reset your Security System

this may be your anti theft pass key try putting the key in theingnition turn it to the on position and leave it there for 10-15minutes then start the car the car may have to relearn the key