Hey stranger! I switched for the same reason from reddit to lemmy and while I can’t help you with the porn problem… you may want to look into Linux Mint.

There are very easy to understand guides online (e. g. on itsfoss.com you can find an installation guide, recommended first steps after installation, …) and there are communities here on lemmy as well. So this may not be the same or a replacement for the communities you miss from reddit but maybe something new to focus on and a way to get in touch with other more or less chronical online people :)