I think that Esta is used for femenine
and Este is used for masculine

Jeelah has given you your answer, but you might want to think more in Spanish, rather than translate from English. We say "Bob, this is Karen," and while you can indeed translate that literally, and use it without problem, it is common in Spanish to use "te/le presento" in such situations. It may sound formal to your English ear, but it's used in Spanish. And don't forget the personal A!

Sr. Hernández, le presento al Sr. González.
María y José, les presento a mi abuela.
Lalo, te presento a mi hermano.

BTW, when you are introduced, you can reply by saying mucho gusto, tanto gusto, el gusto es mio, encantado/a, etc.

Okay. I understand.

Okay. I'll have to study this. How would you say "this is my son"'

Te presento a mi hijo. (informal singular)
Le presento a mi hijo. (formal singular)
Les presento a mi hijo. (formal plural, informal plural)

On the other hand, if you are, say, holding a photo and showing it to a friend, you would point to your son and say "Este es mi hijo."

Agreed. But it is used much more often, and less formally, in Spanish than the corresponding form in English, and that is the point I was trying to make. That is, whereas "I present my son to you" would almost never be said in English, it is used in Spanish, in the settings that you mention.

Language learners always start out by translating literally from their native language, and it is sometimes painful to break that habit.

Thanks for mentioning the "Conoces a mi...." That's a really good way of saying this it if applies.

This is my son/Este es mi hijo (Proximity)
This is my son/Ese es mi hijo (distance)

Las formas de los adjetivos demostrativos son las siguientes:
.............................................. this, these .........that, those ..........that, those
............................................................................(nearby) ...........(far away)

masculino singular . . . . . . . . este . . . . . . . . . . ese . . . . . . . . . aquel
femenino singular . . . . . . . . . esta . . . . . . . . . . esa . . . . . . . . aquella
masculino plural . . . . . . . . . . estos . . . . . . . . . esos . . . . . . . aquellos
femenino plural . . . . . . . . . . . estas . . . . . . . . . esas . . . . . . . .aquellas

Demonstrative adjectives show or point out any person, place, or thing (noun).
Todos los libros de español son buenos, pero yo prefiero este libro/ All Spanish books are good, but I prefer this book.

1. -Demonstrative adjectives agree in gender and number with the nouns they modify, and they generally precede them.

-Esta casa nueva/this new house
-Aquellos árboles grandes/those big trees (far away)

This is what I wanted to know.

Thanks for this information.

Yes, you're right. It will probably take me a couple of years to break the habit.

Even after many years of speaking Spanish, I still do it a lot.

We do what we can do, right'

Can be used too, EL (masculine) or ELLA (femenine)
El es mi hijo; Ella es mi hermana. in an informal atmosphere.

Right. I have a lifetime ahead of me to learn.

Got that too. Thanks.