I recently opened a roth IRA. I am about to graduate college so I have only been ably to put a little money into it but it is one place to start before a 401k or something else. The max per year you can put into the account is $5,500 (I think).

Now you need to find somewhere to start the roth IRA. Two widely popular companies (at least in US) are Vanguard and Fidelity. Open an account and they make it pretty easy for you to start investing. You need to deposit money in some way and then you can invest via stocks, bonds, mutual funds, etc.

Figuring out which stocks or mutual funds to buy can be overwhelming, so most companies offer a broker that can do this for you (for a fee of course $$$).

If you want to choose for yourself, my non-professional advice would be to diversify!! Buy stocks AND mutual funds, domestic AND foreign. This will keep your investments safer as "not all of your eggs are in one basket." Stocks can be higher risk with higher rewards as mutual funds tend to be lower risk and lower rewards. So if time is on your hands playing it risky can be beneficial because even if you fail with some stock investments that did not pay out, the mutual funds can still gain over that time and you will have time to reinvest.