You can add "please" in several parts of a sentence. The most common are the end and beginning.
END: "Write this for me, please"
BEGINNING: "Please, write this for me"
In English, I feel that the sentence feels more polite when the "please" is placed at the end. Yet, politeness works a little differently in the way where we add phrases to make things sound more polite.
ex: "Would you be able to write this for me, please?"
ex: "Could you write this for me, please?"
And when you do this, the "please" can come in the middle of the sentence (which also sounds more polite)
ex: "Could you please right this for me?"