Here are some resources to help you on the PT journey including a couple specific to the many uses of "por" in Portuguese:
"Por" in PT can be used in the English sense to mean many different things including "through" as in looking through a doorway. That is because other languages are not just English with different words. =]
To be fair, English prepositions are just as daunting to native speakers of other languages (and even among those using English their entire lives).
And so it goes...
"Eu converso com os meninos" or "Eu falo para os meninos."
Though I suppose it could also be, "Eu falo aos meninos" with the Portuguese "a" meaning the English "to" contracting with the article, "os" in this case (otherwise too many vowels together). For girls it could be "Eu falo às meninos."
I am hoping someone will correct me (with an explanation). But my sense of it so far is that "a" is more of a destination than a direction concept.