Do you mean that you need the point defined by the parameter on an Edge ? If yes then try the following:
Standard_Real aFP, aLP, aP;
gp_Pnt aResultPnt;
Handle(Geom_Curve) aCurve = BRep_Tool::Curve(TopoDS::Edge(theEdgeShape), aFP, aLP);
aP = aFP + (aLP - aFP) * Parameter;
aResultPnt = aCurve->Value(aP);
The Standard_Real "Parameter" value is the parameter clamped to 0 -> 1 parametric space.
The gp_Pnt "aResultPnt" is your result.