If you are interested in using the WikiTree Sourcer browser extension to help you add citations and add profiles there is a video here.
There is a WikiTree channel on youtube and a new overall intro to WikiTree here.
Hi Nancy. Welcome to G2G!
A number of helpful videos are linked from this page:
https://www.wikitree.com/wiki/Space:WikiTree_TV
This Biography Creation Helper page has a section on adding Sources with some explanation, as well as links to some videos.