New homescreens are added “on demand”:
- Add widget or app icon to homescreen
- Tap and hold that widget/app
- At the bottom of the homescreen you see a little + sign next to the small circle/dot that indicates the current screen. The + sign is probably to the right of the circle/dot. This means that you can create a new homescreen on the current one’s right hand side.
- Drag the widget/app to the right edge (as if there were another screen) and a new screen will be created.
- Drop your widget/app there.
Now you have two homescreens.
If you remove all apps/widgets from such an extra screen, it will be removed automatically.
[Edit: This question is also answered in this longer list of potential problems: Fairphone update 1.8 bugs/issues + fixes collection! Please check before posting!]