To make changes (Add parents, Add child, Add partner,...), you use the sidebar (on the left).
Once you've entered the data (names, dates, locations,...), in the upper right corner, above your tree, you should see 4 buttons: "Save", "Share", "My Account", "Logout"; click the "Save" button and the sidebar should go back to all grey boxes.
If you don't see those, something is definitely wrong. Take a screenshot and attach it to this question.
