Wrong order: assign footprints first, then generate the netlist. Open PCBnew, import netlist.
Tip: PCBnew stacks all components in a large single pile somewhere on the sheet. Select the manual placement icon from the top tool-bar, then right-click in the sheet for a menu. Click "Global Spread and place" -> "Unlock all footprints", right-click again for the same menu item, then click "Spread all footprints".
Before importing the netlist, first create the outer boundaries of the PCB: select as working layer (drop-down menu in the top tool-bar) the Edge.Cut layer, this is the actual PCB layer. Roughly draw the outlines of the board, then use the edit option for each line/curve/object to precisely position it on the X/Y axis. You'd need some spacial awareness and math skills for it though By default components are on the top layer, flip them to the bottom of the PCB (i.e. the underside) with the F key.