How could I invest stock in facebook with out a broker?

[Mopes]

Find the company on the web and send them an email or call their investors relation department to determine if they will sell direct in a dividend re-investment plan. They probably do not so you need to find a discount broker that will open an account with small amount of money. Look for ads that say what minimum account is required. You can buy one share of a stock at a time but the cost may not make it worthwhile.
Look for "Investing for Dummies" ( this is the title not an insult to your intelligence) and read before risking any money.