Un-zip the archive you have downloaded. This can be done by right clicking on the downloaded archive (.zip file). If the file ends in .rar you might need WinRAR to un-zip it. Find your cstrike folder and open it. Inside there should be a folder named sprites. If there isn't a folder named sprites you must create it! Open the sprites folder and paste in the sprite (.spr file) If you are asked to replace any files click "Yes."

You have now installed your new scope._