I was watching tutorials on YouTube of finding and modifying this file called "_zombiemode". The problem is, there's supposed to be this folder called "maps" inside the folder of the map that I'm making, but I can't find it. I would send a screenshot that I took of the location of the folder in the YouTube video and a screenshot of me trying to find this folder, but I can't even seem to upload a picture in these forum messages, either. When I try to select "insert image" when typing up this message, nothing happens. So I suppose that's two issues I have. Just a newbie here trying to figure everything out. Your help would be appreciated!

...file called "_zombiemode". The problem is, there's supposed to be this folder called "maps" inside the folder of the map that I'm making, but I can't find it...

Take a look into the raw folder inside your root directory and you'll find a folder called maps. Search for the files you want, copy and paste them into your maps' folder and done.