Each chromosome consists of one continuous thread-like molecule of DNA coiled tightly around proteins, and contains a portion of the 6,400,000,000 basepairs (DNA building blocks) that make up your DNA.
Repetitive DNA can have preferred insertion sites. In this example, yellow represents the distribution of mys (a type of LINE) over a mouse genome where chromosomes are orange. There are more mys inserted in the sex (X) chromosomes.