While you can use iptables to configure (override) the firewall’s configuration, in the GUI’s “start menu”, under one of the configuration/system menus, there is a “Firewall Configuration” there, which opens up “Gufw”, which is what is used to configure the firewall for organization, simplicity, and ease. “ufw” stands for “Uncomplicated Firewall”, with the “G” likely standing for Graphical.
I’ve left several presets for you to choose from (all of which can be further customized to your liking), the default being Local Administration Only which blocks off access to SSH and other remote administration service ports, with 2 other profiles for remote administration, one allowing SSH access, the other allowing SSH and Webmin access. In the new version that I was working on over a year ago, there were even more profiles for you to choose from.
Edit: You can also use “gufw” and other applications remotely if the remote PC also runs Linux or you have the appropriate software installed on Windows, otherwise you’d use “ufw”.