Help - trying to combine a state-machine file with a bdf schematic

You can use the "create HDL from current file" in order to obtain a VHDL or Verilog file that can be added to your project and instantiated in the top level entity.

Otherwise, if you prefer schematic, you can "create symbol" from current file.

This creates a symbol that you can instantiate in a top level bdf file.

I've no clue on how to handle the active low/high levels of the pushbuttons in the automatically created state machine.