How do I fix my texture appearing backwards? I am a blender "noob" and I am following this tutorial 

Now, I have two problems. First, I have no idea of what nodes go where, and second, the world is in the mirror dimension.
Probably you just need to open UV Editor, selecet all uvs and scale on X Axis with a value of -1, which will mirror uvs back to normal

You can also mirror with a vector mapping node on shader editor