Marasiella,
Click Start on the bottom left of the screen. Click Explore, then Mydocuments. Click on EA Games, then Sims2, then Downloads. Then, go to Program files. Unzip the file into the downloads folder using WinRar or another program. Click EA Games after that, then go to Sims2 (no matter how many EPs you have, always go to regualar Sims2). Go to CSBin and double click on PackageInstaller. Then go to your downloads folder and get the Sims2 Package file, which would be named Caio, probably. Double click on the Package file. Then, click ok when the Package Installer tells you what the file contains. It will say that you have downloaded the file.
Next time, go to the Help section or find a tutorial for downloading. Sims2 Wikipedia has some valuable information on downloading.
And for the sim, Caio is amazing! I have over a hundred downloaded eyes, and none look nearly as amazing as this. Thank you so much for sharing your talent