I want to add a girl on facebook, but i don't want to be like a stranger or creepy?

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I rarely talk to girls, because i'm shy. So i remember this girl from last year at school that i liked, but i didn't go talk to her. She was in my class. I remember she often say hi or hello to me. It was the end of school, thinking i'll never see or meet her again. I don't know how to contact her. I typed in her name on facebook and found her profile. I really want to add her, but i am really nervous on sending a friend request to her. She might not remember me, and i think it might be creepy if she saw my friend request and it would look like i'm stalking her, but i am not. I am interest in her for long time.