I put the Ubuntu .iso file onto a USB drive. I went into BIOS. I changed the boot sequence to put "removable device" first. I did everything the page asked me to do, but the computer did not seem to recognize there was anything else but Windows when I restarted the computer. Is there something else besides the iso file that I need?
Also, if you want another way of choosing boot device, usually holding F12 when your computers starting up will open the boot menu that you can select your USB from, just a little faster than going into BIOS.
Other than that, what Enes said.