These websites allow you to fill in the blanks with your source information, and then they format the citation for you. You can then copy and paste the results into your document. While these websites can be real time savers, they are not foolproof. They work best with straightforward citations. You must enter the information accurately and completely, and you must verify the results.
Remember to specify CMS format.
Also know that the 17th edition of CMS was just published and most of these citations builders have not been updated. If you choose to use them remember to check each citation and make the necessary changes. Pay close attention to punctuation.