For a webpage/website, journal article, or book, you’ll need 1-2 pieces of basic publication information. For example:
Website: URL, page title, etc.
Journal article: Article title, DOI number, author(s), etc.
Book: Book title, author, date published, etc.
Using those pieces of information, you can search for the source in the Cite This For Me APA citation generator and it will help you to create a citation.
Other source types (newspaper article, video, government document, etc.) will provide a form on which you provide all source information. Using that information, the citation generator will create a properly formatted APA citation for you.