I've been a career day trader since 2010.
It's true that most stocks only go up a dollar or so. To make money, you need a lot of investment capital to toss around. Instead of buying 50 of those stocks, you'd want to buy 500 instead. Also, there are more ways to make money in stocks than buying low and selling high in the same day. You can execute a short sale, which is the reverse (profiting from a stock's decline in price.. Kind of complicated to explain here; Google it) Or you can select stocks with high dividends (portions of company profits paid to investors) Dividends are not a huge amount; a few bucks per share at the most. But if you have a good amount of shares in a growing company, it can provide some REGULAR income (when you're responsible for singlehandedly earning every paycheck of yours, you'll miss regular income; trust me.) A combination of "buy-low sell-high" and dividends, maybe with a short sale thrown in once in a while, should get you a dependable income from the stock market.
You can make your trades online with Sharebuilder, eTrade, or many others. They do charge a small fee per trade, though (usually $8 or so) This does cut into your profit, which is why it is important to buy a large volume of shares when the price is about to increase. There are a few online brokerages that allow you a small number of free trades per month (about 30, for most) but if you're trying to become a professional day trader, this won't work for you... When you get good at it and learn to profit from those ups and downs, the little fees will seem insignificant. If you're going to trade online, you'll need to make sure you have a reliable internet connection, and a backup plan if the internet goes down (like going to a family member's house to use their connection, or being able to connect to WiFi on your laptop or smartphone) If you live in a country where the internet can be irregular at times, this could potentially cost you thousands of dollars in bungled up trades!
It was a very gradual transition; you can't just quit your job and expect to make millions on the stock market right off the bat. You have to slowly develop your investing skills and profit. It started off as a small trickle of extra income, then became more significant with time and practice. After about 8 months I was able to downgrade to a part-time job and focus more on my trades. And about a year later, I was making a full-time income from day trading! If you have 8 hours to put into it, it really grows. It's easier than you think; there are a lot of services out there that can tell you (with pretty good accuracy) which stocks you should buy/sell or hold onto. OF course, they're not right 100% of the time (nobody can be) and it's not magic, but they do provide a lot of valuable information to take into consideration when making your trades. The best one I've used is Daily Market Advantage (here's a review: http://stockmarketsystems.org/wp/daily-market-advantage )
There's also a book called The Four Pillars of Investing by William Bernstein; very good book for those trying to break into the stock market game. It dispels a lot of myths and misconceptions about how the stock market works, how you profit from it, etc. It's on Amazon or probably any other online bookseller.
My final and biggest piece of advice: DON'T INVEST WITH ANY MONEY THAT YOU CAN'T AFFORD TO LOSE! Because that may happen. Not likely that you'll lose 100% of it, but just don't count on getting all of that money back if the investment doesn't work out as you planned. e.g. don't stake your kid's college fund or the rent money on a trade!