as the title says..I created it, don't know if right. It doesn't do anything. what should I do? Thanks..(I have some grub problems)
Have you checked the ISO for errors ? If not then do this https://help.ubuntu.com/community/HowToMD5SUM .
If everything is fine make sure about First Boot priority set to RemovalDisk in your BIOS settings .
When your computer powers on, it will show you what key or key-combination you need to press, to bring up a boot menu. For example, on all remotely recent Dell machines, you hold down F12. On some machines you have to press it at just the right time, as it's shown on the screen.
Once you've done this, you'll get a menu where you select your boot device. Select the USB device.
Many machines don't support giving you a choice between more than one USB device to boot from, so you might have to unplug all other USB drives to make it show up in the menu. (You don't have to unplug things that aren't drives, though. For example, if your keyboard and mouse attach to your computer with USB, you still don't have to unplug them.)
If you have additional USB drives you want to read or write data on from the Ubuntu live USB environment, you can simply plug them back in at any point after selecting the live USB device from the boot menu.
If you have further trouble, please comment in reply to this question and/or edit your question, and please tell us the exact make and model of your computer.