Adding Formula to make dashboards

Adding Formula to make dashboards

I have created a formula that needs to auto-populate the result on to the tables then i want to display the information on the dashboard but i am getting several errors.
1. on creation there is an error that the field will not be displayed during creation or editing
2. i cannot view the field on the form
3. i cannot get the data in the data table.
What should i do here.
Rgds