If you're talking about trading shares, forex trading or something like bitcoin trading and doing it for yourself with your own money then you can do it at home with your computer.
It is of course very risky, and as a novice you're likely to lose a lot. That's why it would be worthwhile gaining some experience with minimal risk by buying something like $20 worth of bitcoin and trading that. That's something that you can do at any time without asking anyone or needing to be employed by someone. You'll lose most of it at first, call that your training fee. Once you've made back your losses and begin to consistently make more profit than losses then and only then is it worth investing a larger sum of money.
Make sure to read up a lot about trading strategies too, understanding why the market does what it does is vital, predicting trends is a form of crowd psychology in many ways. Most markets suffer from heavy manipulation by 'whales' too, especially bitcoin. Getting caught out by that a few times and then learning how to profit from it is good experience too, and as you'd only be playing with $20 at first you don't have enough to lose to be worth crying about if it all goes wrong.
Whatever you do, don't start out with a large sum of money because if you get burnt, which you probably will then that'll be disastrous as well as seriously demoralising.
Edit: Yes, it involves endless staring at graphs and coffee drinking until your head hurts. I trade bitcoins, the problem with this market is that there's no end of day, trading is 24/7 so I miss out on a lot of sleep and the market has a bad habit of becoming most active whenever I stop watching it. With the stock exchange it all stops at 5pm and everyone can go home/log off until the next day.
You can make good money like me with this binary option signal software ( http://forexsignal.kyma.info ) Binary options trading has always been popular, however, this investment fad globally exploded around 2008. Originally known as digital options, binary or the name "two values" was added to give a simpler explanation for trading options. Binary is defined as two values or up and down movements. Binaries rely on underlying assets or derivatives. You can trade in commodities, the forex (foreign exchange market), commodities as well as stock indices.
You can work for fund companies.
I'm 15 and have been looking into trading shares for years now and would love to have a career related to stock trading but I can't find any information, about where they would work, anywhere on the Internet. Your help would be extremely appreciated... (I'm talking about trading shares not selling shares to clients, like a stockbroker)