To install kvm on ubuntu:
sudo apt-get install qemu-kvm libvirt-bin ubuntu-vm-builder bridge-utils

For the virtual machine manager

sudo apt-get install virt-manager

To make a qcow2 hard drive image:

qemu-img create -f qcow2 disk.img 4G

Examples to boot an image using qemu:

# From a floppy img
qemu-system-i386 -fda floppy.img -boot a
# Install to hard drive from cd image
qemu-system-i386 -cdrom cd.iso -hda myhdd.img -boot d -m 256 -localtime