Build Path Problems?

Ok. Im a noob at programming, I have the same amount of skips as Java code as how to tie shoe laces. So bad it doesn't exist.

Im following this tutorial: https://www.youtube.com/watch?v=lIbuTTl0M7Q

I downloaded the version said:
Eclipse IDE for Java EE Developers
Forge: 1.8 11.14.3.1450
Java Development Kit 7 - Mac 64 bit - version 7u80

I have 57 Java Build Path Errors, and they all say missing required library.

Im on a iMac.

Let me tell you what I did:

1: Downloaded.
2: Made folder and put Eclipse app in folder. Then, I put the Forge folder in the mod folder.
3: installed JDK
4: In terminal, cd forge folder name.
5: Did ./gradlew setupDecompWorkspace, then, after, ./gradlew eclipse.
6: It didn't work, found out to add "sudo" before the 2 commands.
7. Did it. Opened Eclipse, saw errors.

Im bad at coding, so don't yell at me.
How do I fix these Path errors?
If ya need the error messages, ask me. its just: "Missing required library: Lol/lol/lol/lol/lol"