I would like to as how to add more isolines to a shape or remove them.
Do you mean actually add more knots to a shape, which means adding or removing control points(via InsertKnot or RemoveKnot, for example,) or just adjusting the number of what Rhino calls “isocurves” visible on the surface, which can be adjusted object properties under “Isocurve Density?”
Well just going down the isocurve path, I found where to edit the isocurve density number and turn on their visibility, but for an example I created a simple box from the solids menu and set the isocurves to 10, turned on but all I get is two isocurves for each surface of the box. Why can’t I get more.
The box you created is an extrusion object. Rhino is set up to create extrusion objects when it can by default, that will include boxes and cylinders from the solid menu. Rhino does not show more isocurves on extrusion objects.
You can change this behavior by running UseExtrusions and setting the output type to polysurfaces. Afterwards, newly created boxes will be polysurfaces, not extrusions, and you will be able to change the isocurve density.
You can convert existing extrusion objects to polysurfaces with the command ConvertExtrusion.