> this is an example provided by the manufacturer of the board
Well that's a good place to start.

Have you tried to run it and study the operation?

> I am really new to C programming
Yeah, this is going to be a long haul for you.
C is hard work at the best of times. Embedded / low level C like what you're looking at is even harder.

There will be very few direct answers in the reference documentation and examples.
It's up to you to try all sorts of things and see how they might be applicable to your problem.

Expect (and embrace) the failures, because you're going to have many.
But it's all a good learning experience if you persevere.

I don't have the board (or the time) to lead you through the process one line of code at a time.

UART documentation
PIN documentation

From reading some of the documentation, it isn't quite the "bare board" you're making out.
There does at least seem to be some kind of "TI RTOS" underneath your code.

So, final question.
What TI provided library are you using to read the RSSI information to begin with?