how to convert 3d autocad to solid edge 3d?
AutoCAD 3D is not a solid model. It is basically a group of lines and surfaces in 3D space, therefore Solid modelers don't recognize its output. This is not a Solid Edge problem, none of the other modelers will be able to read AutoCAD 3D files.
If you know someone with Autodesk Inventor, ask if they can read Autocad 3D files. Inventor is owned by AutoDesk like AutoCAD, I suspect they allow some sort of file exchange. Good luck and stay away from AutoCAD:)