Start by understanding the switch.
DMM and paper/pen...or lookup switching schemes and study that.
DPDT is what 'X-Wing' depicts, I believe.
All you need for the wiring suggested is SPST.
Say you have the 1k in there, now add a wire to one side...it'll go...
Wire>Switch>1k>back to other side of resistor that's in there.
When switch is in position B, a 1k reisistor is connected in parallel with the 1k resistor on the board [=500ohms]. In position A, the switch lifts one end of the 1k resistor so the resistor on the board is 'default' ... [1k].
meaning either one, or two 1k resistors are in parallel between the relevant nodes of the circuit.
,,,side note, you can mess around with the values also.
the switch simply adds a parallel path.
Based on the idea that two = value resistors in parallel divide in 1/2 the value compared to 1 resistor.