Divide the electrical system (excluding your new meter) of the car in four categories.
1. The battery.
2. The starter.
3. The alternator.
4. The rest of the system.
The battery has a big wire connected to the starter. This circuit must never, never, never be run through the ammeter.
When you're finished this is how it's supposed to be:
Battery connects directly to starter.
Alternator main output connects directly to main feed of "the rest of the system". Note that "main feed" in this case may consist of more than one wire!
Ammeter connects with + to the above main feed, - connects to battery positive terminal.
link about ammeters:http://www.sw-performance.com/Tech/0tsQAVvA.html
if you dont unserstand how to install it, go to a shop.