Add in your spouse is extremely easy.  

  1. Navigate to your profile by clicking on your profile photo in the top left of the screen.
  2. Under the household section select "Add New".
  3. Enter the required information for your spouse.
  4. Select the "Email Invite" button over the email field.
  5. Save.

An invite will be sent to your spouse's email and they can click the link and create their account using the email address that the invite was sent to.  Once this is completed you will both have access to the household account.