How to add custom tasks?

Hey folks, I added tasks.json file with some tasks inside .theia folder. Now as per the documentation link theia should pick the tasks.json file and show me the tasks inside the menu that comes when I click F1 key.
However there no tasks of tasks.json.

Am i missing something?

Key F1 does not show the quick pick panel of tasks. You need to click Menu => Terminal => Run Task... to choose the task you need.