Xcode for C Implementation - Random Generator - Environment Problems

When you have a few files (see below), how do you get them all working inside Xcode for a C implementation?

These are the files that I’ve been given for this project: 
pcg_basic.c 
pcg_basic.h 
pcg32-demo.c

Project guidelines: http://www.pcg-random.org/using-pcg-c-basic.html

I am also unclear what should be copied to the main.c file. Can't get a grasp on this.

Apparently you also need to link the code with the pcg_basic.o. (not sure how to do that, either)

I know the code does work because it was developed by an expert in this space. But everything I try in Xcode ("fails to build"), so I presume it must be the way I've set things up.

What am I doing wrong?

[*Student here. I am totally new to programming. Thanks]

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