Hello,
You can submit them online through the CRA MyAccount portal or contact the CRA by mail or fax. You have 90 days from the mailing date to file a Notice of Objection with the Appeals Division of the CRA.
For more information about:
The Notice of Reassessment, please visit the TurboTax Blog: Federal Notice of Reassessment in Canada
What should we do after receiving the Notice of Reassessment, please go to the TurboTax article: How to Change Your Tax Return AFTER You’ve Filed
Online adjustment on tax return, please go to the CRA site: Change my return: Online adjustments for income tax and benefits returns