Sort of gets the point across but .
The ammeter connects the battery feed to the main splice.
The Alternator powers everything electrical when the engine is running.
The only time alternator sends power through the ammeter is to recharge the battery.
What you need to know
Ammeter connections:
Red wire must connect to the R terminal on the ammeter.
Black wire connects to the other terminal.
Get that backwords and the ammeter reads backwords.
The conductors
must be insulated from grounding.
Fuse Box:
One feed is always hot. it comes direct from the main splice.
A second feed is hot when the key switch is in run and accessory.
Each of those feeds connects to either two or three fuses.
One fuse is for the dash lights and is seperate, usually on the end.
This is a '67 but yours is probably similar.
Red w/ stripe 12 ga wire is comes from the key switch.
Black 12 ga wire comes from the main splice.
If the car has options, like A/C, it may have a fuse in the middle connected to one of the feeds with a jumper on the buss.