do i need this to install it? http://www.amazon.com/LG-Electronics-Portable-External-GP65NB60/dp/B00ODDE33U/ref=pd_cp_147_2?ie=UTF8&refRID=17TJB4T7SHDXXC6QMXXF
You can install Windows 10 with a USB.
can you do it for free?
The installation itself you can do without purchasing anything (except possibly a USB if you don't have one). You'll obviously need to purchase a copy of Windows though if you haven't already.
what if i want to use the disc version?
You can use the same product key in a USB install. Though if you really want to use the disk for some reason you would need to purchase a optical disk drive.