how to keep in contact with some1 after establishing a friendship? :')

okok I need help ok there's someone really cool at my school who I'd never talked to before, but I always thought he looked cool... well, a week ago, he followed me on insta (O_O) so like obviously I followed him back! Yay! But we've still never talked before so I spent a week freaking out about reaching out to ask if he wanted to be friends so MY friends were all like "omfg Marshall just talk to him" so I did but know I don't know how to start talking without trying to seem to desperate or anything :,) I sat with him and his friends at lunch today (kinda) but it was really awkward idk what to do T_T AND we have no classes together  T_T