Song Construction

I pretty much stumbled upon this method of constructing a song. I came across it when I was learning a song called Romance Anonimo. This song has a simple melody that was made completely on the 1st string. The 2nd and 3rd strings are used for harmony, and the 4th, 5th and 6th string are used for keeping rhythm and providing depth to the song. The method is pretty easy to do and you get good results. This method basically splits the guitar into three parts: high strings, middle strings, and low strings.
The high strings consist of the 1st and 2nd strings, the middle strings consist of the 3rd and 4th strings, and the low strings consist of the 5th and 6th strings.
The high strings are used to give the basic melody of the song.
The middle strings are used to provide harmony to enhance the melody
The low strings are used to keep a steady beat and provide depth as well as harmony to the song.
Now, you should construct your song in this order:

1. Melody (High strings)
2. Harmony (Middle strings)
3. Bass (Low strings)

Let's take a look at how Romance Anonimo was constructed by taking a look at the 1st half of the song. First we will look at the melody. They are all quarter notes played in 3/4 time.

Romance Anonimo Melody

MP3
Now we will take a look at the harmony by adding it to the melody.
Now we will finish off the song by adding the low strings.

Romance Anonimo

MP3