without the quotes;
"list disk" this will show the current drives connected and the size
"select disk 1" this will select the disk 1,
make sure you select your USB drive
"select partition 1"
The drive should be bootable. In case this doesn't work problably the usb will need to be formated, just follow these commands instead of the others:
select disk X "Substitute X with the number of the desired usb"
create partition primary
select partition 1
Now add the Windows Recovery files or any bootable files and boot from the flash drive if the BIOS supports booting from USBs.