Your USB drive should be called Untitled and formatted as Mac OS Extended (Journaled). The installer should be called Install OS X Mavericks.app and should be in your Applications folder.
Run the following command to prepare your USB to be a bootable installer, Don’t worry.. it takes 20-25 minutes to finish..
$ sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Mavericks.app --nointeraction
You should see something like this:
Erasing Disk: 0%... 10%... 20%... 100%...
Copying installer files to disk...
Copy complete.
Making disk bootable...
Copying boot files...
Copy complete.
Done.
You can then boot up from the USB by holding down the option key, then install the Mavericks from the USB.