In general you want to hold the bind button on the receiver or put a bind plug in it depending on what kind of receiver it is and then power it up (while holding button or with bind plug in). Once the receiver is powered and waiting for binding you go to your transmitter/controller and navigate the menus to find the bind option (or hold a button/switch while turning on to get into binding mode depending on the transmitter). Typically on the transmitter if using OpenTX it will have different protocol options in the first setup page for the model near the bottom of the "page" (have to scroll down to find it or scroll up to loop back to the bottom of the page). Once you have D16 or whatever the right protocol is selected you'd go to the Bind "button" and hit enter to get the transmitter searching for the receiver. It should only take a couple of seconds usually you'll see the light pattern on the receiver change but not always. After that just try to exit out of binding mode on the TX (can stay on the page) and restart the quad, hook the quad up to a computer and download betaflight configuration tool:
Are you ready to fly?
betaflight.com
(scroll down get a "release" for your operating system). If first time ever setting this up and using windows you may have to install the STM32 drivers and/or Silicon Labs drivers (can do both won't hurt anything to have them on the system, they just allow windows/betaflight configurator to "see" the flight controller on your quad as a serial device). If using Mac or Linux you should have built in drivers that work for accessing the FC so nothing extra to install.
Once in Betaflight configurator and have your quad plugged into computer with a micro-USB cable you should be able to hit the connect button in top right and get a connection to quad then on the left side will see Receiver tab, click that to see the values coming from your receiver (and if bound your transmitter), if your binding worked you'll be able to move sticks and see values in the Receiver tab change. If that's working as expected next step is setting up your modes/switches (deciding which one arms etc.)
If first time working with betaflight recommend watching a vid or two first on it then watching specific ones for whatever you're trying to accomplish, JB (Joshua Bardwell) on YouTube has an encylopedia of videos on how to do various things in betaflight:
