In the requirement's right side vertical menu, click the time log icon and then the add button. Enter the time and short description. Added times must be at least 5 minutes, and the date must be after the project start date. Time may not be added for dates in the future.
Users must have project permissions to view the requirement to perform this action. Depending on the settings of the user's project permissions, they may be able to view all the project requirements or just a subset. Users added to a specific requirement as a contributor or reviewer will be able to view it.