open terminal and type
to download the bin file of unetbootin
make it executable by typing
chmod u+x unetbootin-linux-313
you have to install p7zip for the proper working of the software
sudo apt-get install p7zip-full
sudo ./unitbootin-linux-313to start the application. look at the screen shot
you can select the distro given in the drop down menu if you don't have the iso of the distro. it will be automatically downloaded from the corresponding website.
it will be better to choose the next option if you have the iso file of the distro. pls enter the path to the iso file.
plug the pendrive to the usb port and select ok, after a few minutes, depending on the size of your distro, it will be installed to the pendrive.
reboot and boot from the usb. here it goes.........