The following are steps to set the JDK(Java Development Kit) path easily
1.Click on Start
2.Right Click on Computer>Properties
3.Click on Advanced System Settings
4.Click on Environmental Variables Button
5.Click on New
6.In the variable name field type PATH
7.In the variable value field enter the path in which JDK is installed (usually C:\Program Files\Java\jdk1.7.0_05\bin),include the bin folder.
8.Click on OK
9.Open CMD and type javac.exe or java.exe or the name of any executable,it will be launched.
See the video tutorial for more information