You will need to know your TD Ameritrade account number and your document ID. Your document ID will be located on your TD Ameritrade statement or Form 1099-B Proceeds From Broker and Barter Exchange Transactions statement. If you do not know your document ID, you will need to contact your TD Ameritrade representative to obtain this information.
If you have trouble importing from TD Ameritrade, try importing through GainsKeeper.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.