Take baby steps – take your pup out. Sit out the stoop. If he seems fine, take a small walk down the steps. Stop. If he still seems fine, take a few more baby steps. Try to take notice of WHEN he begins to feel nervous. Once you’ve identified this nervous spot, take note and assure that you calmly and safely re-introduce this ‘scary world’ to your pup with praise, treats, and happiness. This helps the dog to become desensitized to what frightens him.
And as always, practice, persistence, and patience are key! At times it may feel like nothing works, but keep at it, and in time it will get better.