In order to add call outcome for a specific lead, such lead needs to have a call that either started or it's in Past calls. You will be able to see all information in the Contact Card journey as well.
Navigate to 
Global Data and follow the next steps:
Locate the Lead and click on the Contact Card in the contact column
As soon as the Contact Card is opened, you'll be able to add outcome from Journey pane on the right or to switch to Calls tab
Click on "Add Outcome"
Select "Sale" or "No Sale" outcome
If Sale, add objection and deal details
If No Sale, add reason and objection for an unsuccessful sale