Guide to creating bootable Win 7 USB
After you create the bootable usb.
Reboot your laptop with the usb still connected.
Enter "boot options" by pressing the the corresponding function key, usually F10-could be different. You normally see a message like "Press F10 to enter boot options"
Once you enter boot options you will see the pen-drive listed along with the hdd and DVD drive.
Select your pen-drive and hit enter.
Follow the on-screen instructions.