Dorothy, if you are, as Susan speculates, asking about the DNA Connections section that appears on profiles, those are people (mostly WikiTree members, and a few recently deceased people) who are related to the person on whose profile they are listed. Even if you are also related to that person, it does not necessarily mean that you match others who are listed. You need to compare your DNA with theirs one by one. To do that, you both either need to be on GEDmatch (or one of the other sharing sites) or to have tested with the same company.
If you are asking a more general question about understanding DNA, see Help:How to Get Started with DNA.
