I would like install Ubuntu enterprise cloud in virtual box and need to test it, will UEC can be installed successfully in Virtual box & where can i get Tutorial for that.
No you can't. UEC requires hardware virtualization, as far as I know.
You CAN use OpenNebula with software virtualization.
You're going to take a drastic performance hit running virtualization inside of virtualization though.
I haven't tested it, but if you want to try UEC on the cheap this may work.