There are a bunch of guides to show you how to "Install Windows 7 or Windows 8 form USB Drive" on the internet. You can choose to use the command line, or you can choose the faster way by using Windows 7
USB DVD Download Tool (4 steps) or
UNetbootin (2 steps). I just installed my laptop yesterday using UNetbootin, so I write this to show you how. Just follow some simple steps.
Step 1. Install UNetbootin into your computer. I prefer this one because it can run smoothly in safe mode.
Step 2. Just follow whatever it says.
Note: If you receive the error like this one: "
windows cannot be installed on this disk. The selected disk is of the GPT partition style", you just delete all and create your own partitions.
Have fun!