Tab to or mouseclick on the molecule and use the following keys for interactive exploration:

AActivate keyboard driven exploration
BActivate menu driven exploration
EscapeLeave exploration mode
Cursor downExplore next lower level
Cursor upExplore next upper level
Cursor rightExplore next element on level
Cursor leftExplore previous element on level
On SafariYou may need to use keys E, S, D, F to navigate.
XToggle expert mode
MDe/activate direct magnification
NDe/activate stepwise magnification
ZToggle subtitles
CCycle contrast settings
TMonochrome colours
LToggle language (if available)

See here for some more detailed instructions.