While all users may enter their own actually performed activities, only only users with a role planner or admin have access to this feature.
Select the Actual menu and then the button Approve log. The screen shows you all user in your account (you may sort them either alphabetically or as per the number of hours yet to be approved).
To approve the activities, select the user, review the entered logs and tick the box to confirm.
You may then export actuals, say to feed an external invoicing system, by simply using the download icon on the top right corner of the screen