When you have a 3D view displayed in the Frame, Load or Plot windows, you can control the angle of view by using the rotation controls at the bottom and right sides of the window.  The axes indicator indicates the current angle of view.

The control at the bottom controls the rotation about the y axis while the control on the right hand side controls the rotation about the x axis.  You can click in the control to move the angle of rotation to the position of the mouse.  If you hold down the mouse button after clicking in the control, you can rotate the structure back and forth until you have the desired angle of rotation.  If your structure is too large to draw rapidly as you rotate it, Multiframe will draw a partial outline of the frame.