I put new car stereo in and now the car want start

Check fuses
I found fuse box diagram which one of the fuses is for Theft-Deterrent Module, Radio. I would go through and check fuses
Chevrolet Lumina (1997) - fuse box diagram - Auto Genius
Some info no theft-deterrent below
1997 Chevy Lumina Car Will Not Start. "security" (2carpros.com)
Security System Preventing Car From Running: Car Will Not Start, ... (2carpros.com)

Firstly remove the stereo system and see if that fixes the problem as if it started after you installed it then you have interfered with the power systems for the ECM. Best have the stereo system fitted professionally if that is the case.

you have a serious electrical problem. It is related to the stereo. Disconnect the stereo and hard wire the stereo system directly to the battery with an inline fuse. My spidey senses tell me you are in a german/ european car? Major elevrtoical issues/ design.

see the diagram attached. and fix it. God bless you

Is it an aftermarket stereo? I know vw dont like these and give you lots of problems. Check the wiring at the back of the unit for chaffing too. :)

check it out with a multimeter ,but i think your jump leads may not be any good and you have just flattened the battery ,but check the big fuses in the power distribution box under the bonnet

I would check with a local auto stereo store for an installation kit, which should include a bracket for installing the new stereo, and a wiring harness to connect the new stereo with the car's existing wiring.

the radio that come with car is program to pcm .if remove or put in another radio. pcm security mode kick in.it dont recognize radio it think theft so it disable car ignition so you cant start.if you get a radio the dealership has to put them in and program it.

have all the fuses been checked. if so remove the radio and see what happens

It sounds like a wire somewhere in the wires that run to the speakers is getting a short. Something very similar happened on my mothers car. I trouble shot it and eventually found out it was the stereo that needed replacing.
You can buy a new stereo anywhere that sells them. Be cautious of used as you never really know what you are getting. Installing a new stereo is not very difficult but you have to make sure you have everything you need. You can get everything you need at your local electronics store. Just go to the mobil audio section and tell them which stereo you want and that you need the stuff to install it. All the places around where I live have free instalation with the purchase of a new stereo. Most after market stereos will require a dash kit to fill in the space left over from the size difference between the factory stereo and the after market stereo.