Your retained earnings account will automatically reflect the annual profit or loss at the end of each fiscal year. This amount rolls into the designated retained earnings account without a posting document, so if you run a General Ledger report you will not see a debit or credit to this account. 

Your retained earnings account can be designated by navigating to Admin Panel > Accounting Settings or Accounting > Accounting Settings. Within the accounting settings, you can also designate when the fiscal year for your business will begin. 

In the example below, you will see that the annual net income ($8,475,439.71) and the previous year-end retained earnings balance (-$101,154.35) combine to give a new retained earnings balance ($8,374,285.36) at the beginning of the new fiscal year: