Hi Raju,
Depending upon whether Processing control for the DBT is offline or online, you'll need to execute TPM27 or TPM18 to post the derived flows. The system will automatically calculate the gain/loss and post to the configured GLs.
Incase you aren't sure, you can try TPM27 first in Test Run mode and check if system is posting any entry. If no, you may try TPM18 again in test run and verify the entry.
Best,
Rohit