Step 1: First Install the JAVA Software In your computer System.
Step 2: Go to C > Program files > java > Jdk(folder) > bin and copy path from address bar as shown in below.
Step 3: Right Click on My Computer>goto Properties> Advanced System setting
Below window will appear.
Step 4: Click on Environment Variable , below screen will appear.
Step 5: Click on first and above NEW button and type
Variable name: Path
Variable Value: (Paste the address of bin folder that we had copied);.;
Step 6: Click OK OK
Then Start Command Promt and type javac will show java is install on your computer system.