You import Thinkorswim trades into a trading journal by exporting an Account Statement CSV from the platform and uploading it, or by auto-syncing through TD's API. In Thinkorswim, click Account Statement, set your date range, click the three lines button in the upper right corner and choose "export to file" then save and upload the file, with the correct file ending in AccountStatement.csv.
When you use the broker import option, only Thinkorswim will let your journal automatically recognize your options strategies.