You will undoubtedly need the proprietary driver for your video card, but the first thing to do is a full update of the system.
Login at the command line you get with username and password (password will not show on screen but will be there) then use commands
Now try booting again to see if that is any better, but if not reboot again and hold shift at boot to get the grub menu, and on the line you want to boot (usually the first line) use the E key to edit the lines of the boot stanza for ubuntu. Go to the kernel line that ends "quiet splash" and delete those two words and replace with "nomodeset" which may get you to a GUI, even if it is the wrong resolution. There are many other boot options to try as well as nomodeset so search around for them as well.
sudo apt-get update
sudo apt-get upgrade
Now you should be able to use the "additional drivers" item in the menu, or dash in 12.04, to get the video card driver needed. You can even do it from the command line if you are comfortable with that using
but regrettably I don't know what the package name will be for you to use.
sudo apt-get install <package>