The lighting designer's key tool is the lighting control console (or 'light board'). Understanding the capabilities and functionality of the console is invaluable to the designer.
Because the primary function of all consoles is to bring lights up at particular levels at various times during the show, the general makeup of each is similar. However, the way that the designer and console programmer interacts with the console varies greatly from board to board.
A pretty good breakdown of console use can be found HERE.
While in many cases, you'll be paired with a good console programmer (or board op) you should get to know the consoles that are used in the theatres in which you work intimately. Gaining a familiarity with other consoles is a really valuable resource as well. Many console manufacturers have made offline editors available for free, which is a great way to learn consoles that you don't own.
Here are some links to popular consoles