When you run VPOP3 without it having been configured, then you will be given the option of running the Setup Wizard. The Setup Wizard will configure VPOP3 for a very simple, but typical, configuration, with a single ISP mail account. Everything you configure in the Setup Wizard can be modified easily later, so it is usually a good idea to run the Setup Wizard as it will configure things that you may otherwise miss.
You have the option of Skipping the wizard or running it. If you skip the wizard you can check the Don't ask again box so you won't be prompted to run the wizard the next time you log in.
If you have skipped the wizard and want to run it at a later stage, in your web browser's address bar, go to http://<server IP address>:5108/admin/index.html?firstconfig=1. Note that you should not do this if you have already configured VPOP3 as it may overwrite some of your settings.