The MyHeritage employees have been posting a series of articles in the MyHeritage Blog explaining how DNA works and how it is useful for providing information about one’s family origins. Some of the articles include videos that explain some of the topics covered. Five of these tutorials have been posted so far.
If you would like to learn how DNA works, you might want to read these articles. Start at: https://blog.myheritage.com/?s=DNA+Basics+Chapter.