When you apply a plan or add a shift manually the shifts will be added in draft by default. Draft shifts are only visible to admins in your account. Surfers can only view these shifts when they are published.
To publish shifts to your surfers, click on the publish button in the top-right of the schedule. Then, select the period you wish to publish and click publish.
When you have published your shifts they will fill with colour. This means that your surfers can now see these shifts in their own surfer account.
If you edit a previously published shift, the shift will go back into draft. This means that the surfer can still see what the original shift was, but not your edits. To share this edit with surfers, publish it again.