I don't even know where to begin. Please help.

Hi Zac!

Let's go step by step. At the beginning, you are given this code:

struct RGBColor {
  let red: Double
  let green: Double
  let blue: Double
  let alpha: Double

  let description: String
}

First thing you have to do is this: "Your task is to write a custom initializer method for the object. Using the initializer assign values to the first four properties"

So, you have to write initializer method which should assign values to constants red, green, blue and alpha via given parameters. Imagine you were given simple struct called Person with 2 properties (name, age) and you should do the same here. Look at this:

init(name: String, age: Int) //if I want to have instances with different values in 
//properties, I have to write these properties as parameters
//Here I have declared a parameter name of type String and a parameter age of type Int
{
self.name = name //I want to assign value of parameter name to the variable/constant name
//This is how you do it. We use self to help Xcode realize which 
//side the variable/constant declared in this structure is
//This way we know that the name on the left is the var/let
self.age = age //Same here
}

The other task is: "sing the values assigned to those properties create a value for the description property that is a string representation of the color object".

Again, we will do the same with my made up structure Person. I want the description look like this (if the name is Marcus and the age is 23): "Hi, I am Marcus and I am 23". This is how you'd do it:

description = "Hi, I am \(name) and I am \(age)"
}

That's nothing but String Interpolation. You may find more about it here: https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/StringsAndCharacters.html

If there is something you don't understand, just ask me and I will explain it to you :)