Let's start at the very beginning
A very good place to start
When you read you begin with ABC
When you sing you begin with Do, Re, Mi, Do, Re, Mi
The first three notes just happen to be
Do, Re, Mi, Do, Re, Mi
Do, Re, Mi, Fa, So, La, Te
Oh let's see if I can make it easier

Do- A deer, a female deer
Re- A drop of golden sun
Mi- A name I call myself
Fa- A long, long way to run
So- A needle pulling thread
La- A note to follow so
Te- A drink with jam and bread
That will bring us back to Do, oh, oh, oh

Do- A deer, a female deer
Re- A drop of golden sun
Mi- A name I call myself
Fa- A long, long way to run
So- A needle pulling thread
La- A note to follow so
Te- A drink with jam and bread
That will bring us back to Do, oh, oh, oh

Do- A deer, a female deer
Re- A drop of golden sun
Mi- A name I call myself
Fa- A long, long way to run
So- A needle pulling thread
La- A note to follow so
Te- A drink with jam and bread
That will bring us back to Do, oh, oh, oh

Now children Do, Re, Mi, Fa, So and so on are the tools we use to build a song
One you have these notes in your head you can sing a million different tunes by mixing them up like this
So, Do, La, Fa, Mi, Do, Re
Can you do that?
So, Do, La, Fa, Mi, Do, Re
So, Do, La, Te, Do, Re, Do
So, Do, La, Te, Do, Re, Do
Now, put it all together
So, Do, La, Fa, Mi, Do, Re
So, Do, La, Te, Do, Re, Do
Good! But that doesn't mean anything!
So we put in words, one word for every note, like this:

When you know the notes to sing, you can sing most anything
Together!
When you know the notes to sing, you can sing most anything 
Do- A deer, a female deer
Re- A drop of golden sun
Mi- A name I call myself
Fa- A long, long way to run
So- A needle pulling thread
La- A note to follow so
Te- A drink with jam and bread
That will bring us back to Do

Do, Re, Mi, Fa, So, La, Ti, Do, Do, Ti, La, So, Fa, Mi, Re,
Do, Mi, Mi, Mi, So, So, Re, Fa, Fa, La, Ti, Ti
Do, Mi, Mi, Mi, So, So, Re, Fa, Fa, La, Ti, Ti
When you know the notes to sing, you can sing most anything
Do- A deer, a female deer
Re- A drop of golden sun
Mi- A name I call myself
Fa- A long, long way to run
So- A needle pulling thread
La- A note to follow so
Te- A drink with jam and breadThat will bring us back to 
Do... Re... Mi... Fa... So... La... Ti... Do
So, Do, La, Fa, Mi, Do, Re
So, Do, La, Fa, Mi, Do, Re
La, So, Fa, Mi, Re...
Tiiiiii, Doooo
So, Do