how to setup windows 7 or 8 from USB drive by boot

step 1:

1. start power ISO 
2. insert a pen drive which you want to make bootable
3. choose the "Tools > Create Bootable USB Drive". create bootable USB drive window will popup .
4. select the .ISO FILE of windows 7 or 8
5. select the usb drive
6. click start button to create bootable USB drive

  step 2:

1. reeboot your pc
2. get into the bios configuration by hitting f1,f2 etc
3. go to the section that contains your boot device
4. choose your pen drive as boot primary
5. save all changes