Pls help needed

How the hell do I ask a girl out .
I like this girl from my grade who I kinda confessed to on valentine's day this year and she VERY SWEETLY rejected me by saying we aren't friends like YK not that close and stuff (I confessed as a idk kinda joke but I was half sayin the truth and half joking) sooooo timeskip to now , I like can't talk to her properly without my heart going hsiwksdkwksjjs , I can easily lead a convo with anyone but with her my mind goes black and my heart just wants to burst out and whenever I talk to her my HEART FOR THE REST OF THE ENTIRE DAY WILL GIGGLE AND STUFF HELPPP. IDK WHAT TO DO is it just like a SIMPING thing or an I crushing on her or am I delulu and just admiring her in a friends way ?
Btw I'm also a girl , I DON'T EVEN KNOW MY OWN SEXUALITY. HELP GANG