I'm posting this because I think I can do a better job of explaining and detailing everything from start to stop. :)
A "broker" is just someone who connect buyers and sellers - a middleman of sorts who is easy to deal with. There are many kinds of brokers; the ones you'll most commonly hear about these days are "mortgage broker" (for arranging home loans) and "stockbroker". The stockbroker helps you buy and sell stock. The stockbroker has a connection to one or more stock exchanges (e.g. Nasdaq, NYSE) and will submit your orders to them in order to fulfill it. This way Nasdaq and NYSE don't have to be in the business of managing millions of customer accounts (and submitting tax information about those accounts to the government and what-not) - they just manage relationships with brokerages, which is much easier for them.
To invest in a stock, you will need to:
- identify the brokerage firms which are available to you
- select one of those.
- Consider fees, account minimums, and what sort of trading tools you need
- A brokerage like ETrade will offer you fancy options and futures and conditional orders and things like that, plus an iPad app, and an RSA dongle to secure your account... but you probably don't need all those. And their fees are higher than many other brokerages' fees.
- If you already have a retirement account of some sort, you may be able to open an account at the same financial institution, which could be convenient for you even if their fees aren't the lowest. For instance, I like Vanguard, but that's mostly because they have nice mutual funds and cheap-ish stock trading; their stock trading interface actually stinks.
- open an account at that broker
- provide personal information, including your social security or taxpayer identification number (so that they may check your credit and report your income to the government)
- read the fine print. do not just skip reading the fine print.
- provide the broker with money (for instance, provide them with your bank account number and transfer money via electronic funds transfer... or mail a check)
- use the tools the broker provides you to place a trade - in your case, you'd probably want to buy several shares of Facebook at the market price, a "market order".
- The broker will charge you a commission, usually $5-20. They will charge you this again if you sell that stock. If you're not investing more than ~$200 in a stock, it's almost certainly not worth it to incur these fees. Lots of $1000+ are more fee-efficient.
- Also, be aware that you probably won't get to say "buy $1000 of this stock". You'll have to say "buy N shares of this stock at the current price" and hope that works out to around $1000. The current price will change several times a second. You may also make a limit order, saying "buy N shares of this stock, but only when it's at a price no higher than $X a share". This is a little more predictable, and if there is a better price out there you'll still get it.
- Be prepared to report your stock gains and losses to the federal government on your form 1040, schedule D. Or be prepared to hire a professional to do the same. It's kind of a pain. If you are currently using 1040EZ, be aware that luxury will be GONE.
- (Your brokerage will mail you tax documents, typically form 1099, at the beginning of next year.)
- If your state government has an income tax, you'll need to file a form there too (e.g. California form 540).
In this day and age, most brokers that you care about will be easily accessed via the Internet, the applications will be available on the Internet, and the trading interface will be over the Internet. There may also be paper and/or telephone interfaces to the brokerage, but the Internet interface will work better.
Be aware that post-IPO social media stock is risky; don't invest any money if you're not prepared for the possibility of losing every penny of it. Also, don't forget that a variety of alternative things exist that you can buy from a broker, such as an S&P 500 index fund or exchange-traded corporate bond fund; these will earn you some reward over time with significantly less risk. If you do not already have similar holdings through a retirement plan, you should consider purchasing some of these sooner or later.
