You can port forward on the port forwarding tab in your dashboard after logging in. You need the following when opening a port:
After opening the port, and want to test if the port is successfully open, you can use canyouseeme.org.
Before using this website, you need to have something actively listening on the port and you should either turn your firewall off or allow the program and port through your firewall. Otherwise it will say it's closed.
If you receive the following error when trying to open the port: "Port xx is already opened by another user on our xx, xx Server!" this means that someone else has this port open. You will need to use a different port or try a different server.