[TYPO3-commerce] Show extra column in backend -> Orders -> Order Data Page

[Peter Waechtler]

hi,
i would like to add the column paymenttype to the overview page. so  
that i do not always have to go into the order to see which payment  
type is used.

ther are two things i do not understand here:

1. why is the column '[payment]' in the overview not show anything
2. how to i add the column paymenttype to the overview?

thanks in advance,
repiet