Remotely SSH into home computer that is coected to a VPN

I have a computer at home that is coected to a PIA VPN. I've been trying to figure out how to remotely ssh into that computer while it is coected to the VPN using port forwarding provided by PIA, but I caot figure out the correct way to specify the SSH command. I'm fairly certain it is possible because I remember figuring it out once a while ago, but I can't seem to remember how I specified it and have been trying to figure out what arguments I should be passing.

First I tried this:

ssh user@LocalVPNIP -R 22:PublicVPNIP:FPort

where PublicVPNIP is the public IP that is assigned to my computer from the VPN, LocalVPNIP is the private IP that is assigned to my computer from the VPN, and FPort is the port that the PIA client says it is using for port forwarding. What is the correct way to specify the ssh command for this?