@PurpleChick
Okay, so with Potato, when you first open it, you'll see the standard kind of stuff at the top. Just click on File>Address Book. This will open up a new window within Potato. Click New World from the selection of items towards the bottom. It will pop up another dialogue window. Add in the Name section "DC Rebirth" or whatever you want to call the game. Then in the Host section type dcrebirthmux.com. In the Port section, type in 2001. Click Okay. On the Address book window, click close.
You're ready to connect to DC Rebirth, at that point. So, just click File>Connect To>DC Rebirth. You don't have a character yet, so you won't have anything to save for a character. Just click "No Character".
You'll see the log in screen of the game. It will prompt you for your name and password. You'll see three options here. Just type "connect guest" and press return. This will bring you onto the game as a guest. In the first room, I think you'll have to type "I agree" and that will bring you into the nexus room where you can talk to us on game and we can go over some commands with you and talk about what characters we have available and what you're interested in doing.