Once you have JMV started, and have a file loaded, navigation is very simple. The molecule appears in the main canvas and the controls appear below. The mouse controls to orient the molecule are:
Left button: Rotate Middle button: Zoom (Moving the mouse down zooms in, moving it up zooms out) Right button: Translate
On 2-button mice, the controls are:
Left button: Rotate Left button + ALT: Zoom (Moving the mouse down zooms in, moving it up zooms out) Right button: Translate