I Think My House is HAUNTED!

OKAY so the other day my roommates and I were at my apartment and i swear to my good lord above there was somebody standing out on my balcony. The three of us were inside. Then another time we were all three sitting on my bed on the computer and we all three see a shadow go by in the kitchen. It kinda freaked us all out! I really don't know where this ghost came from. He/She just showed up. Then one of my roommates was here by herself and she was in the bathroom putting on her makeup and she felt sombody walk behind her and her hair moved and then it touched her shoulder, i got home about 10 minutes later and she was sitting on the stairs outside the apartment terrified and crying. So tell me what should i do about this random ghost???