i need windows 7 trailar

hi all

i was many times looking for windows 7 64bit trilar , the temporary one
i have a usb flash drive and i want to install the windows into it but i didn't find it online
can any one give me any trusted website or link to download it and how i set it to my usb flash drive

i have usb flash drive 4GB and it is compatible with all windows edtions and versions

waiting for your answers

thank you already