VF31 need to add new field on selection screen.

Hi Masters.

I need help with VF31 transaction.

Our customer give us order to expand VF31 transaction, exactly selection screen.

He want new field with document art (FKART).

How can i add this field to sel screen and in second step change procedure to get data to get this field as additional condition.

Can you help me ?

Thanks

Sergiusz