word choice - When to use "come" & when to use "go"?

I don't understand what this article is saying:

We use come to describe movement between the speaker and listener, and movement from another place to the place where the speaker or listener is. We usually use go to talk about movement from where the speaker or listener is to another place.

When we talk about another person (someone who is neither the speaker nor the listener), we can use either come or go, depending on whether the speaker sees things from the receiver’s viewpoint (come) or the doer’s viewpoint (go).

[doer]Yolanda came to [receiver]her mother for help.

We use come when we see things from the receiver’s viewpoint (in this case the mother).

[doer]Melissa went to [receiver]her mother for help.

We use go when we see things from the doer’s viewpoint (in this case Melissa).

Could you explain it clearly?