How do you manage the national quest building you have been appointed officer for?

If you were appointed by the president to receive a presidential buff and are now in charge of the national buildings for the next week, you have only one very simple job - placing cards for your building.

You can place 2 of your own cards that you've already obtained by ranking yourself up in national quests. Then, you can purchase an extra 2 cards using an item called a "Wolf Fang Pendants". They cost 500 diamonds each, and the first "extra" card costs 1 pendant, and the 2nd costs 3. These generally provide better stats than the cards you have unlocked.

To place these cards, simply view your building and click the empty card slots at the top. This will take you to a screen that allows you to set cards.

While you can theoretically do this at any time during 'business hours', it's highly recommended that you do this within the first 5 minutes after reset. From what I have witnessed so far in-game, any time-reduction cards will not be effective if placed after a group starts marching to your building - but it appears the Exp cards do count if placed before your visitors leave (they are not retroactive in the sense that someone who has already left will not benefit from you placing cards at all).

And there appears to be a fifth card slot that requires a different item than the wolf fang, but that item is not yet available for purchase and therefore you cannot place all 5 cards at this time.