how did huck end up living with the window douglas?

This happened as a result of the previous book Tom Sawyer. Huck went to the Welshman's house because he saw Injun Joe and his sidekick by the Widows house and they mentioned slitting her nostrils and Welshman and his son went out with guns and fired and scared Injun Joe away. The Widow was so grateful that she took Huck in to raise him and civilize him.