Assign and follow up a task

How to assign a task for an an employee so he get notification and i can follow up what he has done

You can set up notification based on some trigger like filling up a field, or change in some value etc on the task doctype. Check this link to know how to set up notification: https://docs.erpnext.com/docs/user/manual/en/setting-up/notifications

At the project-level, you can also set up “Project Updates”.

Hope this helps.