Howto move cam in lookdirection?

Hi, guess this is a newbie-question, but I was not able to find it out for some hours now:

I have a space with some boxes, where mouseclick can pick them, but if nothing under the mouse,

I want that a press of the left button and drag will move the user(cam) forward in look direction (or turn if sidewards), speed depending how far the drag is.

When I’m right there are two ways to archive that cam movement?

To ‘fire’ a KeyForwardAction to my present (My_)FirstPersonHandler?

Something like:

’ forward = new KeyForwardAction(cam, 2.0f);

input.addAction(forward, “forward”, true);

but that seems not to do anything.

The second way may be more difficult to compute the new pos x/y/z of the cam by rotation?

Anyone can help me or already have such a different FirstPersonHandler-code finished?

Mille thanx in advance!