After Installing module, Go to sales.And click on button shown in image.

A pop-up will open where you can add groups for header.

Give a name to group and add columns by dragging.

your Test group is created with selected columns.

• fill all the required details.
• After completing that, Click on "Add P&F" Button.

you can create multiple groups at once.

• Product: it will show only products whose P&F field is enabled
• Fixed: it will add price that wont be changed on on-change.
• Percentage: it will add price that would be changed on on-change. (according to P&F Price is Entered)

you can assign who can edit header groups assigning them "Edit Header Access".

If a user does not have edit access, then edit header groups button won't be visible to them. but they can still see created header group just can't change them.