How do I start investing as a 15 year old European? I hear the sooner you start, the better

I would like to start investing, but I have no idea what are the best ways to do it or how to do it. I have no idea if I should invest in singular stocks or Index Funds, which apps should I use, how can I create an account that I can actually use at this age. I have about 600$ capital, which may seem little, but it should be enough for a good start if I can invest smartly. Any help about anything connected to this matter will be greatly appreciated, I’m trying to get as much info as I can from this post.