Click on any of the featured PDB codes or search the PDB database using the text field to the right to load a ribbon model of the corresponding structure. Note that downloading files from the PDB can take up to 15 seconds. After loading the PDB file, you can change the graphics using the options to the bottom-right and interact with the model by using mouse events over the 3D canvas.
toggle rot.: double-click
For more about ribbon models, please read this MacResearch article.