Winlink. Need an explanation

Help me here, I'm new to this.(Correct me where I go wrong):
First question: As I understand it Winlink can, in theory, operate without the internet. It would work like this: I type msg into my computer which has a serial cable to my radio. The radio xmits on a repeater that handles Winlink and it goes to Winlink repeaters worldwide. Assuming the recipient is listening, his radio will pick it up and send it thru his cable to his computer. Where am I wrong here?
Second question: How do I know what repeaters will handle Winlink messages?
Third/Last Question: Assuming the internet is operational, where does it fit in here?
I know this is long winded and I appreciate the help
73
KE8QWY (Steve)

Not sure about serial cable, depends on your radio. I would need to use audio cable with sound card (USB?) to connect to radio.

The people near me using Winlink over RF are using simplex. I have not heard of anyone using or testing it on local repeaters.

Using Winlink through internet doesn't accomplish much, just another email option. It really needs to be over RF to be useful IMO.