I've said multiple times over the past little while that you should absolutely learn CPR. Well, while this isn't a replacement for actually taking a CPR class, here's a blog post I've written up on CPR and a bunch of related topics:

https://aurav.neocities.org/blog_posts/save_life_psa

I will emphasize that this is not a substitute for a proper CPR class, but if you can't take one for some reason or something happens before you can, maybe the info in this blog post will be helpful for you.