You now need to open a CDF document with a 3D graph in it. For instance, download the document from this example from the Wolfram Demonstration Project. Select "Download Demonstration as CDF" from the box on the right of the page as the image below shows. Then use the Open... icon within the CDF Player to open the file from wherever your browser saved it. Note that the images are not just 3D but stereoscopic (I view with crossed eyes but you might have another method).
It is confusing for a newcomer when the browser plugin does not work so you might want to try a different browser if you want to interact directly via the web.
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