An autostereogram is like a magic picture that can create 3D images without needing a special pair of glasses. It's like a hidden picture inside a picture, and you have to look at it in a special way to see it.
To see the 3D image in an autostereogram, first you have to look at the picture without focusing on anything in particular. Then, you have to let your eyes go all blurry and unfocused, like you're staring off into the distance. Keep your eyes relaxed and don't try to focus on anything in particular.
As you look at the picture, you might start to see little dots or lines that seem to float above or below the picture. Don't try to focus on these dots, just let your eyes relax and keep looking. Eventually, the dots will start to form a 3D image that pops out of the picture!
It might take some practice to get the hang of seeing the hidden 3D image in an autostereogram, but once you learn how to do it, it can be really cool to see things pop out of the picture like they're coming right at you!