blh64:
Did you read the description over at SparkFun? SparkFun Analog/Digital MUX Breakout - CD74HC4067 - BOB-09056 - SparkFun ElectronicsYou have to connect 4 pins from your nodemcu to the select lines of the breakout board and the signal pin on the breakout board to an analog input pin. By setting your address pins, you select channel 0 to 15 to connect to your signal pin which you then read. If you look at it in binary, it looks like this:
S3 S2 S1 S0
0 0 0 0 = channel 0
0 0 0 1 = channel 1
0 0 1 0 = channel 2
0 0 1 1 = channel 3
...
I read the material posted on the site about the product, but my question is more of how do I code for it to read values from each individual channel and where do I put the code for the sensor to operate.