Wagon description says that you're supposed to use a "winch" to load vehicles on and off, but there's no winch anywhere in any crafting menu.

So I tried using the ramp, pointing it at a wagon, where it said "waiting for train", so I made another ramp and pointed it at a locomotive.

Neither ramp did anything, driving on them just had me crash into the train.

Finally, I put down a tank wagon, then put a ramp against it and the game crashed with

The mod Vehicle Wagon 2 (4.1.11) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event VehicleWagon2::on_built_entity (ID 6)
VehicleWagon2/script/loadingRamp.lua:78: attempt to index field '?' (a nil value)
stack traceback:
VehicleWagon2/script/loadingRamp.lua:78: in function 'findTrainsForRamp'
VehicleWagon2/script/loadingRamp.lua:124: in function 'setRampVectors'
VehicleWagon2/script/loadingRamp.lua:379: in function 'OnRampOrStraightRailCreated'
VehicleWagon2/control.lua:494: in function <VehicleWagon2/control.lua:471>

I'm just confused as to how any of this works.

Please use the in-game tips&tricks tutorial. The winch is a shortcut tool like the red and green wires. The ramp currently only functions when the train is in automatic mode and the player exits the vehicle.

There is no ingame tips&tricks tutorial for the winch or the wagon.

https://imgur.com/a/UhHOoOM

Also, what of the crash?

Sorry, I don't use the testing scenario so I didn't know it hides all the tips and tricks. I only test in freeplay worlds with the /cheat command to unlock everything. Do that and you will see them.

The crash is because you editor-placed a loaded wagon entity that didn't have a vehicle associated with it. I forgot to handle that case in the loading ramp code. Thanks for reporting it!

That wasn't a testing scenario, that was a freeplay world I used /cheat on.

Then I can't explain why all your tips and tricks are gone. They show up for me even in editor. They are supposed to unlock the first time your character places an empty Vehicle Wagon.

I don't think its screwy on your end, its been weird for other mods as well. Colony builder is supposed to have a builtin wiki in tips and tricks but lots of people report that it doesn't work for them either.

Can you try starting a game with only vehicle wagon installed?

But to answer your original question properly: the way it's supposed to work is you place an empty vehicle wagon, drive a car next to it, get out of the car, click the Winch tool in the toolbar, click on the car, click on the wagon, and press Q to put away the winch.