To track the time spent on a case you must first:
Enable Task & Update timesheets on the project which the case belongs to
Turn on Cases on the project
Be a Case Worker or Case Owner of a Case. (Alternatively you can be a Project Manager or Organisation Admin of a project or organisation that has cases)
How it works
You can track the time spent on
Tasks tagged to each Case
Updates tagged to each Case
Get started with tracking the Time Spent on a Case
Mark the task as done and log the time spent
Post an update tagged to that case and log the time spent
See the Time Spent charts on the Cases page