Is a set of chromosomes made up of many copies of DNA, or is one complete string of DNA broken up into one set of chromosomes?
A chromosome is one long molecule of double-stranded DNA.  As a diploid organism, you (almost certainly) have two copies of each autosomal chromosome; one from your father, one from your mother.  You (almost certainly) inherited one copy of the X chromosome from your mother, and you either have a second one from your father, or you inherited a smaller Y chromosome instead.