The biggest advice I would give is to start early. In your post you mention you're 18 so thats great. Too many people wait until they're in their late 30s or 40s to start investing (usually by then they got a family, mortgage, kids, and need to save for college and retirement simultaneously). I started seriously investing when i was 19. I was in college and didn't have a whole lot of extra money and it wasn't all that sexy or exciting. I would recommend first setting up a Roth IRA. When you start working, max that out every year with the 5,500 you're allowed to contribute.
As far as your individual investments, Investopedia is a great resource for learning the basics. Great place to start. As far as researching specific securities, I have a morningstar.com account. This is a great evaluator of markets, stocks, bonds, mutual funds, index funds, and ETFs. I use this it as the primary research tool for my own investments. I'm long in the market, meaning I buy assets expecting/hoping them to increase in value. I don't trade options, futures, short stocks, or day trade. these are all great ways to lose money if you don't know what you're doing. Look at the stock market as a good place to put your money and let it increase over time, not a mechanism for getting rich quick.
Also, don't get discouraged early on. I have no idea what your financial situation is like but since you're 18, I'm guessing you aren't completely financially independent (which is expected for an 18 y/o). Like i said, I started in college. every time i had a couple hundred bucks extra, instead of blowing it on a night out, i would research a stock/bond/etf and invest it. my money didnt grow quickly because I didnt have a lot. Now i'm almost 27 and make about 85k a year. Instead of going to Vegas all the time or driving a car i can't afford (like a lot of my peers), I make sure I invest between $1500-$2000 a month. I've got a strong and diverse portfolio worth about $125,000 and have no debt. Thats pretty unusual for a 26 year old and i attribute it mostly to my interest in investing when i was where you are. Okay, rambling/claim/obnoxious post over. OP, message me if you have any other specific questions. Best advice i can give is dont get discouraged and stay interested.