Is your DVD movie purchased from shop? It is probably protected and cannot be easily move to USB; btw, DVD movie is in vob format, which is not a unniversally accepted video format. It's better change it to digital format e.g. Mp4. This guide below should help you a lot.
Well usually dvd movies are about 1 gigabyte in size. So first of all you need a usb thats big enough (1 gigabyte or more) Then if you have the movie ripped and ready on your hard-drive just insert the usb stick. When your computer has recognized the device, open it. Then drag and drop the dvd movie in the usb stick map and wait until it is synchronized. Then eject the usb stick by right-clicking the usb stick icon in 'your computer' and take it out of your computer. Done!