Get the LCD out of the packaging. You'll need some sort of 10K potentiometer. We will use some header and premium socket jumpers but you can skip that part and just solder direct wires.
Solder the header in, then we clip the unused data pins to avoid confusion.
Connect the LED backlight lines to the LCD logic power lines.
Ground the RW pin (it's not used).
And get rid of that pin as well as pins #1 and #2 (they are close to the mounting post so we'll connect to pins #15 and #16 instead).
Connect the 10K pot to 5V, pin 3 and ground.
And clip pin 3.
Now we have the used 8 pins, from left to right: ground, power, D7 thru D4, RS and EN. Connect sockets.
And clip the other end.