Linux

These are terminal instructions and work on Ubuntu, Debian, Fedora and most other distributions.

1 Install WireGuard

On Ubuntu or Debian run sudo apt install wireguard. On Fedora run sudo dnf install wireguard-tools.
2 Move your configuration into place

Download the file from your dashboard, then run sudo mv ~/Downloads/*.conf /etc/wireguard/ followed by sudo chmod 600 /etc/wireguard/*.conf. The permission change matters: the file contains your private key, and WireGuard will warn you if it is readable by other users.
3 Connect

Run sudo wg-quick up <name>, where <name> is the filename without .conf. Check it with sudo wg show, which lists a recent handshake when the tunnel is working.
4 Optional: connect automatically at boot

Run sudo systemctl enable --now wg-quick@<name>.

How do I know it is working?

Run curl ifconfig.me. The address shown should differ from the one you get with the tunnel down.

Run sudo wg-quick down <name>.