REW has given you a good primer. If you want more, same investing philosophy:
It takes some work to learn, but it's not that difficult if you invest for the long term and you devote as much time to the discipline of investing (understanding market history/behavior). Where people get in trouble is just
relying on "tips, or advice" (brother-in-law, friends), thinking they can pick winning stocks/brokers (about 95%+ can't) and or time getting in or out of the market (again 95% can't - and too many people convince themselves they're among the 5% who can).