Exemplar is a software package that helps you work with continuous sensor data. Exemplar is only one part of a larger hardware/software prototyping setup.
On the hardware side, you need sensors and an interface to forward sensor data to a PC. Sensors that output analog voltages are probably the easiest way to start. For an affordable hardware interface, try Arduino. Sensors and interfaces are available through Sparkfun in the US.
On the software side, Exemplar is a Java application written as a plug-in for the Eclipse platform. This means that you will need a working version of Eclipse installed on your computer before you can use Exemplar.
Finally, the events you generate in Exemplar have to be received by some other program, which can be running on the same computer or a different computer on the network.