Are you Single or Married filing Separately? You need to enter a qualifying dependent to select Head of Household. If you entered a dependent it would have automatically switched you to Head of Household if you qualify. Go back to My Info and check all your answers for your dependent.
Do you qualify for Head of Household?
https://ttlc.intuit.com/community/family/help/do-i-qualify-for-head-of-household/00/25539
