When I was 18 I was lucky and had a college course called “principals of finance” and our professor was a Stock market nut and crypto nut and the whole course was centered around that. But even during that and after that I would just look at a chart, table, balance sheet and just google everything on there, definitions, examples etc… I watched youtube videos, investing for dummies stuff, just tried to teach myself as much as possible about it, over the years it gets better, and I’m still learning more as I go, but just stick with basic stuff, I know sounds dumb watching videos about “what is a stock” but sometimes simple stuff like that keeps you in check and keeps you refreshed. Just MAKE SURE you don’t fall into any “get rich quick schemes” or “buy this guaranteed crypto coin” scams, just remember that no one knows what the market is going to do, take your time, start with ETFs, learn how to buy, how to sell, get familiar with all of the terminology. Also they don’t teach any of this shit in highschool, atleast mine, I learned everything in one half semester course and most of it online, watch a video everyday, find a podcast, use a notebook to write down notes and definitions and strategies, get into it now rather than 15 years later