we are suppossed to enter a loop, and prompt the user for a product name and ad it to an array and then prompt the user for the quantity and then store the value in a hash (both of these are accessed later to print on a receipt.)

I have two questions:

1. is the user prompted embedded in the loop our outside of it? The book gives examples of loops dealing with arrays that are hard-coded and not input by users (or at least I cant find one)

From the description above I would say inside the loop.

From your last comment I guess you have familiarized with loops iterating over arrays elements. Of course that's not the only way to deal with arrays (in loops or wherever else). For example:

my @array;
while (my $new=whatever You::Like) {
    push @array, $new if is($new)->good;
}
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2. and I am not sure if I would use a "foreach" or a "while"

A priori both would do. It all depends on how you decide how to do it, TMTOWTDI applies!! However one of them is "more natural" in this situation than the other. You should have enough clues by now know which is which...

PS: to highlight Perl keywords in a visually distinctive manner instead of quoting you can use inline <c> or </code> tags.