If you have not already filed: TurboTax will ask you for your direct deposit information under the File tab once you have completed and reviewed all of your tax information. To access or change your banking information in TurboTax Online you would go to the File section. See this FAQ for more details: https://ttlc.intuit.com/replies/4083015
If you have already filed: You can review the direct deposit account information you entered by looking on your printed return. This will be found on your 1040 under the Refund section (look for line 76).