hello

can you tell me please how to i select a specific color and replace it with another color without changing the shape of the object

also, afterwards, how do i apply effects, shades, gradients, etc at that specific color?

thanks

You can simply select an object and click on the color chips in the palette at the bottom, use Shift + click to change the stroke color. If you need more control over the colors open the Fill and Stroke dialogue (Shift + Ctrl + F).

If you need to replace one specific color with another you can use the Replace color Extension.

You can create a gradient using the Gradient tool, have you tried it?

In Inkscape effects or Live Path effects actually change the path shape, not colors. If you want the lighting applied to an object or similar look into Filters.

Check out the guide from my sig, you'll find it all there