Using the right hand mouse button, click anywhere in the box; a menu will appear. Click on "Rotation" to stop the molecule spinning. Now click and drag the left hand mouse button to manipulate the structure.

Using the right hand mouse button, bring up the menu and click on "Display" to see the various ways of representing the molecule. 

To measure  bond lengths use the right hand mouse button to click on "Select" and then on "Mouse Click Action" in the second menu. In the next menu, click on "Distance", the menu will disappear. Using the left hand mouse button, click on an atom, a label will appear at the bottom of the screen; now click on a second atom, again an atom label will appear, followed by the distance between the two atoms you selected (in Angstrom units, 10^-10m).

To  measure bond angles, use the right hand mouse button to click on "Select" and then on "Mouse Click Action" in the second menu. In the next menu, click on "Angles", the menu will disappear. Using the left hand mouse button, click on three atoms, one after the other. After each click an atom label will appear at the bottom of the screen; when you have selected the third atom, the angle between the three atoms will also appear.