Windows:
Learn more at http://www.ubuntu.com/download/help/create-a-usb-stick-on-windows
Mac Os X:
1
Download Ubuntu Desktop
2
Open the Terminal (in /Applications/Utilities/ or query Terminal in Spotlight).
3
Convert the .iso file to .img using the convert option of hdiutil (e.g.,hdiutil convert -format UDRW -o ~/path/to/target.img ~/path/to/ubuntu.iso)
Note: OS X tends to put the .dmg ending on the output file automatically.
4
Run diskutil list to get the current list of devices.
5
Insert your flash media.
6
Run diskutil list again and determine the device node assigned to your flash media (e.g. /dev/disk2).
7
Run diskutil unmountDisk /dev/diskN (replace N with the disk number from the last command; in the previous example, N would be 2).
8
Execute sudo dd if=/path/to/downloaded.img of=/dev/rdiskN bs=1m (replace /path/to/downloaded.img with the path where the image file is located; for example, ./ubuntu.imgor ./ubuntu.dmg).
Using /dev/rdisk instead of /dev/disk may be faster
If you see the error dd: Invalid number '1m', you are using GNU dd. Use the same command but replace bs=1m with bs=1M
If you see the error dd: /dev/diskN: Resource busy, make sure the disk is not in use. Start the 'Disk Utility.app' and unmount (don't eject) the drive
9
Run diskutil eject /dev/diskN and remove your flash media when the command completes.
10
Restart your Mac and press alt/option key while the Mac is restarting to choose the USB stick.
Learn more at http://www.ubuntu.com/download/help/create-a-usb-stick-on-mac-osx
Ubuntu:
1
Insert a USB stick with at least 2GB of free space.
2
Open the dash and search for Startup Disk Creator.
3
Select the Startup Disk Creator to launch the app.
4
Click 'Other' to choose the downloaded ISO file.
5
Select the file and click 'Open'.
6
Select the USB stick in the bottom box and click 'Make Startup Disk'.
7
That's it! When the process completes, you'll be ready to restart your computer and begin installing Ubuntu.
Learn more in http://www.ubuntu.com/download/help/create-a-usb-stick-on-ubuntu
If your computer doesn’t automatically bring the boot menu, you might need to press the F12 key(or Esc Key) to bring up the boot menu, but be careful not to hold it down - that can cause an error message.
1
Turn on your computer with the usb already pluged in
2
Then quickly press esc or F12 to bring the boot menu.
3
Choose the Usb option and then you do the waint part.
4
Then it's easy just configurate the ubuntu and you're ready.