I'm so attracted to my sister

I'm 24 years old and she's 16, I only saw her two times in my life but I can't stop thinking about her. We do everything to communicate, she's so pretty, nice, smart and sweet and she told me she spent the whole day thinking about me, I need to get her attention, or make her think and stop thinking about me so much, I want to get closer to her in a healthy way. What can I do?