Running error Javac

:confused:
I am the beginner in java program.i face some problem.please anyone help me.i describe problem below.
1)i install java 7 on my pc
2)but there is problem to run it.when i click the desktop icon of the java ,it starts installing.
3)i make a program in notepad and set cmd. but when i type javac lima.java on cmd,javac is not understood by the cmd.

what should i do?
i have an assignment.but i can't understand .
please help me to solve my problem.

Most likely you haven't set the path properly or you skipped that step. When running the javac command, your system needs to know where to find the programs.

Look at this installation guide and check the part where you update the path and environment variable.
JDK 7 and JRE 7 Installation Guide