1. Enter to manacube (manacube.net)
2. Open the menu in your hotbar (compass) by right clicking while holding it
3. Hover with your mouse to the earth in space with a big red flag on it called: "Earth towny"
4. Click it.
Another way:
1. Enter to manacube (manacube.net)
2. Open chat
3. Type: /earth
4. Use the "enter" button.