Firstly, go to the direct message with Workast under 'Apps' on the left-hand taskbar. This is where you create all of your personal tasks.
To view your personal tasks, type: /todo list. That will bring up your personal task list.
Click on the ellipses (three dots) next to a task to bring up the message menu and choose 'Complete'.
The task will be updated with a green check to signify it has been completed.
You can continue with the same process to mark multiple personal tasks as completed.
Quick tip - you can also bring up your personal tasks from any Slack channel by using the /mytodo list command, and you can complete them the same way.