Navigate to the form builder for your app on CommCare HQ
Navigate to where you want to insert the question.
Press the Add Question button and add an "Android App Callout" question type under the "Advanced" tab
Create an ID and label as you would a normal question
Under "External App", select Breath Counter. The following should appear in the field to the right: org.commcare.respiratory.BREATHCOUNT (if for some reason you are using the old app Respiratory Counter, you will need to select Custom and then put in change.uw.android.BREATHCOUNT)
Under "Logic" you can enforce the same things as you would a normal question, IE enforce this must be a realistic value, non-null, etc (validation condition: . != 'null')
Once the user performs the breath counting via the 'Breath Counter' application, the resulting integer value will be passed back to CommCare and stored in the "Android App Callout" question's "Question ID"