Retopoly and uv questions

Hi. I don’t quite understand, how retopology works. Lets say, that i created very high poly model in zbrush, then i need to retopology it in mid\low poly model in zbrush or 3dcoat or topogun (doesn’t matter). But i don’t understand how can i transfer my uv from highpoly mesh to new retopologized mesh, so i can use normal maps from highpoly etc? Or is there quite another way to do so? I just don’t understand how it works.Thanks.

Or i need to retopo model, then uv result and then bake it and highpoly in xnormal?

To get the level of detail of a high poly mesh on to a low poly one you need to bake a normal map. In blender goto ‘Render’ panel > Bake > Bake Mode > select ‘Normals’. Also check the box for ‘Selected to active’

This Tut explains what ‘baking normals’ is about.