Adding folder paths to the Windows path variable


I have a little problem when i install ghostscript the command does not work properly, but i know it because the command does not find then path
and if you find the same problem here it's :

    1.Right-click My Computer.
    2.click Properties.
    3.In the System Properties window, click the Advanced tab, and then click Environment Variables.
    4.If the last character is not a semi-colon (;), add one.
    5.After the final semi-colon, type the full path to the file you want to find.