After installation go to Control Panel -> Display Settings - (or simply click with right mouse button on the desktop and choose 'Properties') and choose Screensaver tab. Select your new screensaver's name in the drop-down list, check the settings (sometimes you can change speed, number of characters, use a password etc). Attention: all screensavers don't work in Preview mode. Sometimes you need to restart Windows to be able to use the screensaver. If you are installing several screensavers just after each other, you might get error messages. Restarting Windows solves most problems. Windows also has an upper limit how many screensavers it can handle - it is somewhere between 50 and 100+ screensavers depending of your hardware specifications.