Traditionally, the correct way to use
will and
shall is as Tiefling gives it. To state it fully:
To express future time: shall goes with the first person, will with the second and third persons.
To express an intention to act: will goes with the first person, , shall goes with the second and third.
It is uncertain whether or not this distinction was ever part of normal everyday usage, or if this is wishful thinking on the part of the
grammarians.
In modern usage, shall has almost completely been dropped from use when talking about the second or third persons, and is used apparently at random when talking in the first person. I have never met nor heard of anyone who insisted on the traditional usage of these words.