Why am i not able to edit my calendar?

You can also access your calendar from your Dashboard. When you are on your Dashboard, at the top right should be the box that says "Available this Weekend ... you can also manage other days in your calendar" and the words "your calendar" are a hyperlink that you can click on.

From your description it sounds like you are on a PC. When you click your name in that top right-hand corner, do you see the drop-down with the following: Dashboard, Profile, Inbox, etc? That's where it should be. If you don't see it there you should contact Rover support.