Now DXF file loaded to the DXF viewer and you can change the unit and scale.
Select Tools → Import categories for editing → Accept.
Select Fabrication manager → Tools → Reconstruct from graphics → Reconstruct board outline →Click on the diagram → Autoreconstruct
Now the diagram automatically convert to as a board outline and also user can see this board outline in Layout editor.
After construct board out line, go to Schematic Editor and draw the circuit and autopackage the components,
go back to Layout Editor, and place the components in the new board out line and draw the traces.
You can take the Gerber output from Fabrication manager with new board outline.