2d scrolling background

What language? Which tools?

Have you tried google? Just enter your language and 2d scrolling, and you'll find plenty of hits.

if you know about scrolling backgound like the game in that link . Please guide me

Could you please specify what you exactly mean by "scrolling backgound"? Because I don't see any background scrolling in the game you've posted.
Do you mean parallax scrolling (like here - foreground is moving faster then background) or just normal scrolling?

just unlimited simple background like green walls in top and bottom of the game that i posted in firts post

This tutorial for XNA covers repeating a background image and parallaxing. I found it quite helpful. http://create.msdn.com/en-US/education/tutorial/2dgame/drawing_the_background