If you have downloaded an installer distribution, run the installer. If you have downloaded JDT as a zip file, unzip the file into a directory of your choice.
Jar File
The JDT library is contained within a single jar file named jdt.jar and located in the lib folder of installation directory. You will need to add this jar file to the classpath of your development environment. When applications that make use of JDT are distributed , this jar file should also be distributed together with the jar files and other files of your applications.
Key File
JDT requires a key file called jdt.key in order to run. The key file can be an evaluation key which you received by email or it can be a permanent key which you received after purchasing a license. The key should be placed in the classpath of your development environment and it should also be redistributed together with the jdt.jar file when you distribute the applications you have developed with JDT.
Installing the toolkit