After asking permission to approach the witness, show the tenant the photograph. Ask the tenant to identify it.
Ask questions establishing that the tenant lives in that apartment building, that he or she uses those stairs, and has used those stairs recently -- the day before the incident being examined in this trial, and on the day of the incident.
Ask the crucial question about whether the photograph represents the condition of the stairs on the day of the incident.
Ask the judge to admit the photograph as evidence.
Be prepared to answer any objections make by opposing counsel.