These Practice pages can be utilized in several ways.

The recommended method is for two partners to be in vocal contact, each looking at the page in a different computer - perhaps one with a laptop. Using this method one partner would start by clicking on NORTH, the other on SOUTH.

Somewhat less satisfactorily, the partners can use a single computer, and alternate looking at the display, again one as NORTH, the other as SOUTH.

As a last resort, one person can click back and forth between screens.

Start by clicking one of the buttons; when the bidding is complete click the BIDDING button to check the "recommended" bidding.
 You are the Dealer.
 Bid this hand with your partner.
 The opponents do not bid.
 Your partner, NORTH, is the Dealer.
 Bid this hand together.
 The opponents do not bid.

After NORTH opens 2NT, SOUTH is pretty sure there will be a slam in s. But, the contract should be played from the NORTH side so the opening lead doesn't go through any vulnerable ♠ holding NORTH might have.

SOUTH transfers NORTH to s, then uses Blackwood to be sure they aren't off two Aces. Missing one Ace he settles for 6.
♠ K 8 6
A 9 3
K Q 8
♣ A K J 2

♠ 7 4
K Q J 7 5 4 2
A 9 2
♣ 9