Here’s a link to a very helpful site that includes video lessons
Here are a few videos about the different kinds of croquet shots used in playing games like Windsor or Association. The man in the videos is Chris Clarke, who, along with his wife Jenny, have played on the international circuit for many years. Here is their website.
This site provides “courses” covering aspects of croquet such as Laws Training, Stroke-Play and Tactical Coaching, Lawn Care, and some fun stuff such as croquet trivia quizzes.
This page defines many of the terms you will encounter when playing croquet.