I need help with my crush..

Sooo, it's my first reddit post because i'm super duper desperate but im 17 and i have this crush on that one guy and urrghh. I don't know what to do! He's super handsome and God his smile, matter of fact his whole face, he's very intelligent even if his grades don't reflect it often and he's a big nerd also he's a year younger than me and we have ONE mutual friend which is also my best friend. My Bsf wants to help me, he wants to set a date up or something like that but i've never been on a date, less one with someone i don't know. Yeah because i've talked to the guy thrice on instagram and twice in real life, that's why i don't say i'm in love because i don't know him well enough to be that attached but also i've seen enough for him to make my stomach do flips and my arms go crazy.
Sorry i've been yapping for nothing, but basically two days ago he posted a story to which i answered saying that he could hold my hand. He answered saying 'thank you very nice of you' and that was it but then minutes later he texted again asking what i meant by that. I was kinda confused if he had caught on the fact i kinda liked him or if he really did not know, but that conversation ended quickly because he just went 'actually it doesn't matter let it go'. So i did, but now i don't know what to do, how to go talk to him, how to engage in conversation that would keep him interested..

My bsf also told me my crush had apparently been rejected by a girl he liked a month ago or so.

So yeah i really need advices, what should i do ? and how should i do it?