Before playing in the 1993 Spring Nationals in Kansas City, I had never seen bidding boxes. It did not take long to learn the basics. Bidding boxes are easy to use if you know how.
The established partnership can accurately describe the strength of their hands by how near the left they begin bidding. If you start on your far left, you show a very good hand since you intend to make a lot of bids. If you start bidding by placing cards on your right, you show a poor hand. If you start bidding in the middle, you show an average hand. If you start in the middle, and then move your previous bids to your left, you show that the auction has improved your hand.
Many partnerships have trouble deciding when a pass is forcing and when it is not. Even if your partnership is fortunate enough to have solid agreements, you will have hands your agreements do not handle well. To make a forcing pass with bidding boxes, merely handle your bidding cards prior to selecting a pass card. There exists a corollary to showing a forcing pass if you are not sure who is sacrificing, touch your double card prior to passing.
When I started playing, people opened one notrump when their strength was right even though they possessed a five-card major. Times changed and virtually everyone opened the major, even with the right strength and shape for one notrump. Now, there is beginning to be a resurgence of one notrump with a five-card major though opening the major is still much more common. Either way you have a problem. With bidding boxes, open one heart with your five-card major. After your partner responds one spade, you can rebid one notrump with a minimum hand or with a big notrump opening. How will your partner know the difference? If you have a minimum hand, cascade your cards as you would normally. With a big notrump. place the one notrump card directly on top of the one heart card (so the one heart card can no longer be seen).
If your partner opens the bidding and you would like to respond, but you really do not have the values to do anything other than pass, handle your pass card and then bid.
If you want your partner to pass, merely hold your last action in your hand do not place it on the table. This works with double (I have them where I want them), pass (do not continue, do not balance, just shut up), or any bid. Suppose you open one club, and partner responds one spade, you bid three clubs and partner bids three spades. Three notrump by you allows partner to correct to four spades. However, if you hold your three notrump bid, partner is not allowed to correct.
I know of two treatments you may use with the stop card. If your partner is forgetful, you want to use the stop card when your bid is preemptive and not use it when your bid is strong. If your partner is reliable, use the stop card only on bad preempts.
If you are unsure about what action you should take, make many motions toward your bidding box without selecting any action.
To show emphasis about your bid (either Pass or Double), select multiple cards. The more cards you display, the stronger your message. Six Pass cards shows a Yarborough. Some players prefer to indicate emphasis by the way they put their bidding card on the table. Slamming means this is the final decision for the partnership. Floating a bidding card indicates resignation. Bidding boxes are a wonderful thing. You do not need to pay attention all the time because you can review without asking for a review. You do not need to worry that other tables will hear your auction. You do not have to worry about what someone bid, did they bid two notrump or was it three notrump. I think if you try them, you will like them.