First you boot from your usb and the installation starts. At one point you have to choose the disk to install to. There you click on advanced disk options an DELETE all the partitions that may be on the disk. The ssd has to be raw when installing windows. Windows will then create two partitions: one for the boot loader and one c: partition for the windows files. Beside that the 64GB is the raw size and 59.6GB is the formated size.