When you sit at a computer and want to control the cursor you might use a mouse. Interactive white boards are exactly the same thing. It is simply a giant mouse that allows you to control the computer connected to it through a large image projected from the front of the classroom.
Whatever you would normally run from your computer can work with the infrared interactive whiteboard. All of the software that you might run from the comfort of your desk can now be run from the front of the classroom. The left mouse button becomes your finger on the SMART or other touch sensitive/camera based boards or the nib of the digital pen on the Promethean board.
In order to start using your IWB all you need to do, once you have all the wires connected, is to orientate or calibrate it. This involves you running a small program which comes with the software provided by the manufacturer. It allows the computer, the IWB and the projector to work together.
How frequently this process needs to occur will very often depend on the kind of set up you have in your classroom. If you have a permanent installation with a separate projector on the ceiling, then you might only need to do this once a day. However, having a class of lively students in a room above yours can sometimes mean that the projector wobbles with the ceiling as they move around above you and can mean that you have to calibrate or orientate the board again. Alternatively, infrared touch frame whiteboards with projectors on a pole or those that use either short throw or ultra-short throw projectors lessen the need even further.
The only other time you may need to calibrate is when you swap from one computer to another. Remember that the calibration process allows the board to understand where the image and the computer meet. You are using the board as a big mouse. If you change the computer then you need to complete the process again so that the board as accurate information. There are also boards which have auto calibration settings which mean that you no longer have to go through this process.