Help Me on Windows 7

I dont know how to change screensaver in windows 7 and does anyone know how to genuine windows 7??I have do a wrong thing...i do a genuine scan on microsoft website and its says my windows is not genuine because I have download many things in my computer...help me...

If you have done scans looking for malware and found nothing, try re-activating Windows. Microsoft has had some problems with the genuine scanner.

To change the screen saver:

Open Screen Saver Settings by clicking the Start button , clicking Control Panel, clicking Appearance and Personalization, clicking Personalization, and then clicking Screen Saver.

Under Screen saver, in the drop-down list, click the screen saver you want to use.

Click Preview to see what your chosen screen saver will look like.

Click OK.