How did /u/NSF_Zebras do this?

Hi, I was recently browsing NSFW subreddits, and I came across this really interesting post:

https://www.reddit.com/r/NSFW_GIF/comments/2dt5m2/an_analysis_of_3600_nsfw_subreddits_for_their_gif/

u/NSF_Zebras wrote scripts to analyze several different subreddits, pulling all sorts of information from them. I think this is insanely cool, and I would very much like to do the same thing. I took a programming 101 course, but I'm not sure how to actually do that. I tried to write a reddit bot to pull comments from a certain sub, but it gave me some error, like I had to register the bot or something.

I'm planning on spending this entire summer learning how to do this, and how to do this well, but I'm not sure where to even begin.