Guy problem (written by the sister of the account holder)

This is a post written by my younger sister, she's written this but I will handle the comments and replies to this story. I'm letting her use my account so she can get advice about this, she asked if she could use this site and I didn't see the point in her making an account for just one problem and she is only 14. Please Help if you can.

I like playing video games and I like rock music and things like that, I use photoshop as well.
Recently, I put a video on Facebook, it's a Youtube video and it's just about a funny glitch in Call of Duty Black Ops that I laughed at. All my friends that are girls commented stuff like "What the hell?" and "Why did you post this?" but then there's this one boy and he commented "YOU play black ops??" this is how the convo went:

Me: Yeah what's so suprising?
Him: Nothing, girls just scream at that sort of stuff.
Me: Yeah well, I'm used to it. It's only fake blood
Him: Prove it, what's your fave gun?
Me: stoner63
Him: I like the FAMAS lol

Then he chatted me on Facebook and started telling me why his gun was more awesome, I said why I thought mine was. He then said I was a girl and I didn't know much about that stuff, I said I knew a lot about it, I also used Photoshop and video editing stuff and I knew how to talk about the graphics of the game too, he said he used YouTube so he knew how to edit. He had to go but then these weird things started happening. I looked on his YouTube channel at music he'd been mixing and commented that I liked it and told him how he could make it better, but didn't tell him it was me who said that because I didn't want him to be sexist to me again, instead when he saw my real name on my channel and he said thanks for being cool about it, but then at school I was partnered with him and this other guy for Computer Studies and he said "Hey, you might be offended but look at this..." and he rolled up his sleeve and on his forearm he had tattooed in Biro ink, a swastika! I didn't say a thing but I was really really offended, my granddad was Hungarian and forced to fight for Nazis, which I know he didn't know but I wondered why he would show it to me if he thought I would be offended. When he went to find a teacher for something the other guy I was working with joked that he didn't really want to show me the tattoo but the muscle on his forearm, because he wanted to impress me. I laughed but then someone else butted in and said, "I saw the little conversation you had on Facebook, he's never talked to girls about that stuff before you know." Which made me feel a little strange, because no-one has ever spoke to me about stuff like that before, since I've never had a boyfriend.
Then when the guy in question got back he started talking to me about things you can do on Photoshop and he's seen my stuff on Facebook (I post it sometimes to get critique from other computer geek friends of mine)and he said it was good but it could be better and would I like him to teach me some things about how to make it better! I rejected, saying that I taught myself but I'd give him a shout if I needed help. He looked a little disappointed and said "Are you sure?" I said yeah and he said "Oh." and didn't talk to me until the next day when in music we were asked to choose two types of music that we liked as part of a quiz that older students were doing. I chose rock and dubstep, he chose the same. Now he looks at me all weird and distant. And his friends stare at me now too! I'm starting to feel unsettled, someone joked that he likes me but I don't think that he does, he talks to other girls a lot more than me and he doesn't know me too well.

Would he do and say those things if he liked me or was he just being friendly? And why the hell are him and his friends staring at me?

Once again this was written by my sister who needs advice I can't give, please be nice about your answers. She wont't read the comments but I'm passing on useful advice :)