How do you care for a car?

Hi I have no idea about cars whatsoever and it’s causing me a lot of problems. 2 years ago I bought a Audi a5 2010 with 62k miles on for 13k and it only lasted me 2 years. My engine was gone and had low oil pressure and low compression cylinders. I only got oil changes and would repair what’s damaged. I didn’t even make it to 100k miles it died out on me at 86k and I junked it. I don’t want to make the sane mistake. How do you properly maintain a car? I just recently learned what a service but still clueless.