<human>: If this question has been asked before, I am really sorry. I am new to reddit and have been having this issue since forever so I would love any type of info you can give me.

Let me start off by saying i am a complete moron when it comes to flirting. As a girl, it has been and still is very hard to figure out when a guy is being nice or if he is interested .Thus,  a lot of moments and awesome opportunities have passed me by, because of this shitty defect. 

For example, i went to one of my university fancy parties and among other people was a guy i find attractive. Really tall, which for me is rare giving the fact that I am 1,80 m. Either way, we never talked, I just noticed him talking to one of my friends one time(let's call this friend Jeff).

So, Jeff at one point in the evening comes up with him and introduces him to me. Then this guy says: Jeff told me he'd introduce me to the most beautiful girl here. I guess I've found her. Pretty obvious right?  That would seem so, unfortunately he has been in a relationship for the past 2 years or smth. All I could say was: A-ha... because of that.

My question : What in hell does this mean? 
If there are any girls/guys out there that can give me a few basic pointers to clarify this issue of what guys do when they flirt/ want something more/ less  please, please just throw some advice my way.

Provide a brief overview of the text.
<bot>: I am a complete novice at flirting and I would like some guiders along the subject of general male-female interaction from a guy's point of view, or girls who know when the hell a dude likes you.