You mean the bezier handles? If so, there's no bezier handles, because they are not bezier splines but B-splines :)
The overall shape of the spline is not based on the direction of handles, but it's an averaged curved path derived from the position of the nodes.
Other than that, the spline nodes are edited with very same Adjust Control Points tools. Just don't expect the Bezier handles. If you really want the hanldes, you can convert the shape from B-spline to Bezier. Select the spline and go to the shape inspector. There, in shape type, select the kind you want (linear, bezier, b-spline).
If ithe problem is something else, let us know.