To Vs Too Vs Two

To is usually used as a preposition.

Examples :

I will give it to you.
To arrive early, we must leave early as well.

Too mean "besides" or "also". Too is also used to show too much of something on term of quality.

Examples :

It's too much to handle.
She is annoying too.
It's expensive, too.

Two is a written number = 2.

Examples :

There are two books on the desk.
The two boys are my kids.