How do I get started in astronomy data analysis?
A possibility might be a course at a university, youtube, or a self-study-course via a book.

What we've used in our astrostatistics class was "Wall &amp; Jenkins: Practical Statistics for Astronomers" which presents theoretical sections with exercises as follow-ups. No answer sections exist, as you need to do some programing for some of them.

But you can maybe lend this or similar books at a local university library, without the need to spend money.