Question

Who does a DNA get to know how to replicate itself and what is actually present una DNA that governed how we look

Answer 1

Both of your questions are extremely high level research topics. I will try to explain them in an understandable way.

How DNA replicates? Well, DNA knows how to replicate, when to replicate. This is because, a DNA has everything , including information, instincts, basic functions , ancestral data, etc.

Human DNA has over 3 billion base pairs. We haven't studied even few million of then and their functions.

Somewhere in these base pairs is the data regarding replication, how and when to.
When DNA is supplied with enough nutrients, it starts replicating. Replication is a basic survival instinct, that has existed since beginning of 1st DNA. The method has been modified by evolution.

And how we look..well our skin color, hair, eye, color, body growth, orientation of muscles, etc are all encoded in DNA.

The DNA gathers these info from ancestors. By evolution, DNA knows where to place organs, and how to shape them. That also includes a small amount of recombintion from our parents, which results in us.

Some characteristics not seen in parents might be seen in us. All these are functions of DNA, and data in base pairs.