How do I NEST sheet metal in solid works ?

There is no "smart" way to do it.
If you had to use SW for this task, the process used would depend on the data you have. Do you have 2D or 3D data to start with?

Assuming it is 3D model data, I'd bring each piece into an assembly.
Make a reference sketch in the assembly which matches the size of the material stock you are working with. Then start dragging the parts around until they fit best on the sketch. Adding a few mates to keep everything on the same reference plane, or to fine tune an angle or position would help.
A drawing of the assembly can be made, then the drawing can be saved as a dxf/dwg file.

Honestly, it is a waste of time though. There are likely a dozen "nesting" programs which would accomplish the task much faster than anyone doing the task by hand.

Maybe there is a SW module/add-in that handles nesting?
Many 3D printer programs also solve nesting problems. I used to use Materialise Magics to layout cut sheets for the production department.

Whatever method you use will largely depend on what format you need at the end.

Here is a plugin for SW: https://nestingworks.com/

Make a form tool from flat piece which you need to nest.
Then open a another part where is a plate which you will cut.
put a form parts on plate

Camworks Nesting is also a plugin for SW and handles everything you need to do all types of nesting. Whether it is a part, an assembly or both, it is also possible to create an inventory of the remaining parts, thus saving time and material. https://www.youtube.com/watch?v=cKee-FvIzN8