Open a brokerage account if you do not have one. Alternatively, you can invest "directly" via Microsoft's transfer agent. Either way, you will need an account which you can use to purchase Microsoft stock from (see Resources below).
Deposit funds in your new account, or if using an existing account, verify that you have sufficient funds to complete your purchase.
Decide how many shares you want purchase, and under what conditions. If you want to buy Microsoft stock today without regard to its current price, you need a market order. If you want to buy only if the price is a certain amount you need a stop or limit order.
Give the order. Whether online, through a broker, or as part of your application, you must instruct the agent to purchase your shares. You must specify the quantity of Microsoft shares you would like to purchase, the type of order to execute (market, limit, stop), and any time limits on the order (Good Til Close or Good Until Canceled).
Verify proper execution of order. Review your trade confirmation to ensure that your order was executed as you instructed.