Selfhosted

I am completely new to the realm of self hosting. I don't know a single thing about how I can self host stuff. Regardless, I have the curiousity to learn it by myself but I don't know where to start. I cannot find any sort of wiki or FAQ articles, nor do I have the ability to ask the forum for every single problem or doubt I encounter during the setup. Can someone direct me to a beginner friendly site that teaches all there is about self hosting and all the questions and misconceptions that come with it?

Additionally, is a self hosted server only accessible inside my home? What about accessing the services outside, like Bitwarden or Nextcloud apps that require syncing and availability of data wherever I am? If it is useless outside, there would be no point for me personally to self host in the first place since I am perfectly fine with using cloud services for now and the convenience that comes with it. Plus, no one else in my family cares about self hosting and I don't wish to spend the effort to convince them to in vain, so setting up a server for convenience of everyone at home is also out of the question.