How do I create a SPICE netlist?
A netlist can be created with any text editor capable of generating an ASCII file. You can view the SPICE netlist of any schematic in LTspice XVII with the command View=>SPICE netlist. From this view you can copy the netlist to the clipboard by selecting all text and typing Ctrl-C to bring the netlist to a different editor.
How do I run a netlist?
Just open the text file first and then run it. LTspice XVII will recognize the file as a netlist if it has file extension of ".cir"