You’re right. I used a fancy term when I should have demonstrated.
Code fencing is when you wrap blocks of code in triple back-ticks. So, 3 of these bad boys: ```
In your post, you would start and end your code block like this:
3 little backticks above
// Heres's where your code goes
3 little backticks below
Code fencing itself is something that Github uses (but might not be a Github invention) and is an addition to Markdown (which the fCC post editor window supports).