regulation of path speed over time

I would like to create an animation where the movement along a bezier curve is not constant over time. In some regions it should be slower than in others. I cannot figure out how to achieve his using the graph editor, because there is only a straight line without any points to edit.
I would really appreciate your help.
Thank you very much!

I suppose you parented the object to the curve with Ctrl+P / Follow Path. This uses a modifier in the graph editor to control the slope.

Instead add a Follow Path Constraint to the object, select the curve in the constraint, enable ‘Fixed position’ and keyframe the Offset value

Just add more points by CTRL-Clicking directly on the f-curve in the Graph Editor. You will be adjusting the slope of the line. A horizontal slope, or a slope of zero, will make the object stand still on the path.

thank you very much for your help.
@Atom: CTRL+Click does not work in the Curve Editor. It sais ‘Remove F-Modifiers’ from F-Curve to add keyframes’

@Richard: Your solution seems simple and effective, but I do not find how to keyframe the offset values. Could you help me with that?

With your mouse over the offset value use RMB / insert keyframe or shortcut I. This will insert a keyframe for the current offset value for that frame. Once you have created one keyframe you will then have access to that channel in the graph editor so you could use that to add and change any further keyframes

Thank you very much!!! That worked fine!

I have another question concerning my camera paths. I have created a bezier circle along which my camera is supposed to move. Is there any way to insert points in the middle of the curve? So far I only know how to extend the path on one end :-/

Select two adjacent control points and W / subdivide.

Thank you!
This forum is great!