what is the translated latin of these words: with, the, of ?

Answer 1

With is "c.u.m". Omit periods.
Of is "de"

Latin did not have a definite article - there is no word for "the"

Also, in many instances where we use "of", there would not be a separate word in Latin. The ending of the noun would change instead.

Answer 2

amicus est in atrio:measns my friend is in the hall