Class B+ winterizing, getting fluid in line.

I got a siphon pump and drained the lines. Got the antifreeze and now I am trying to figure out how to get it in the line.

My freshwater storage is under a seat and connects to the water pump, I pour water in or connect to the city line from there. Ive turned the hot water to bypass. Usually I just dump the water in the tank. So just trying to figure out bypassing it to get it down the line.

It didn't come with a manual.