Im a newbie and i dont know how to connect

Im trying to connect Arduino Uno and APM Planner using the 915MHZ radio telemetry.

My mac is running 10.12.6 and I have downloaded and installed the FTDI. Here is the link I followed, I did the exact same thiing as this: http://ardupilot.org/planner2/docs/mac-install.html

When GROUND MODULE is connected I see cu.bluetooth… and tty.bluetooth.

When Arduino with the AIR MODULE is connected I see cu.bluetooth…, tty.bluetooth, cu,usbmodem, and tty.usbmodem.

How do I connect? what do i do next?

Not sure what you mean by Ground Module and Air Module???

This Link has the connection instructions.

What exactly are you trying to connect?
An Arduino Uno?
You need Ardupilot installed on the board (through the firmware tab) before mission planner can connect to the MavLink stream.

Trying to connect Arduino Uno.
I do not even have Ardupilot just air module and ground module. Can i connect it like this: https://www.youtube.com/watch?v=8zU309jKdtc

I am trying to make a gps controlled little arduino car.

If you want to use an Arduino UNO, you will have to write your own code to control your car. No version of Ardupilot/Ardurover will run on an Arduino UNO. Pure remote control over the telemtry modules is not that hard to do. Controlling with a GPS is harder to do and you will have to use softserial, since the UNO has only one hardware UART.

can you expand more on that? I do not fully underestand. Do you have any link or anything?

If you google/search for “arduino controlled rc car” or similar, you will get plenty of results. Or have a look at Blynk on Android. I once build a remote controlled vehicle controlled with this app.

Yes, I get the RC part. I have already built a rc car but i am stuck on the GPS controlling part. Can you help me?

I have never done anything with GPS and arduino.
Have a look at TinyGPS++:

http://arduiniana.org/libraries/tinygpsplus/