When you click on buttons and other controls like these
a molecular model is loaded or modified in the left window.
(Test them, if you haven't yet done so.)
The first time you enter a page with models, it will take some seconds or even minutes for preparing the model window. Similarly, the first use of a control that loads a model or acts upon it usually has some delay. Please, be patient and do not worry, on successive occasions the behaviour will be more agile. Try also not to reload the page or change the window size repeatedly, nor to use the "back" and "forward" buttons in your browser; you could cause a longer delay or even a lock-up, or the unexpected closing of the browser. Please be patient while navigating through the pages and use the navigation buttons provided inside them.
In this case, a model has been loaded for the thyroxine hormone. Like in this example, in most pages the molecules will start spinning right away, for a better perception of their three-dimensional structure.
Locating the mouse pointer over the molecular model area and dragging while holding the left button you can rotate the model at will. To change its apparent size (zoom in or out), use the mouse wheel or hold the Shift key while you drag vertically the pointer. For complete instructions on handling the mouse, click on the icon in the toolbar (below the model).
In addition, clicking the right mouse button (or left-clicking on the lower-right "Jmol" logo) opens a menu that allows very diverse actions on the model. For a simpler use, you also have several buttons in the toolbar at the lower left:
The standard colour code to represent atoms is called CPK code; it is summarized below the model's area and you can check it out its details by clicking on that colour key.
Finally, to move along the contents you have index pages and some buttons located at the end of each page: