Whether you hold stock certificates, hold your shares in a brokerage account, or have an online trading account, you will need the assistance of a securities firm or a stockbroker to sell your stock. Your company will probably require your shares to be deposited in an account at a specific securities firm or transfer agent. The brokerage firm you use can help you with its procedures, which may allow online and telephone sales.
If you want to sell specific shares (e.g. highest- or lowest-cost shares) according to when you purchased them and at what price, you need to specifically identify them in some way through your brokerage firm's system and receive a confirmation of this. Otherwise, the first shares purchased are considered the first ones sold for calculating your gain or loss on the sale.
Alert: You should confirm that you have certified an IRS Form W-9 or Form W-8BEN for the account with your brokerage firm or transfer agent. If it does not have this form, you will be subject to backup withholding on the sales proceeds.
For details about the tax reporting of the sales, including annotated examples, see the relevant section of the Tax Center.