how can i install after effects again after uninstalling it?

hi my mom and dad just recently bought me an imac

and i have never used an imac before so im kinda confused.

so here is my problem ( please help me )

i can’t open my after effect because it quits on its own

and i was stupid enough to unistall it

there was an icon in finder “ uninstall adobe after effect” and i clicked it because i thought i could install it again and make it work

but now im stuck finding how to install it again

please help me and please use simple words cause i can not speak english fluently 

THANKYOU VERY MUCH, IM AM SO HELPLESS HERE I CANT SLEEP BECAUSE I REALLY NEED IT TO INSTALL AGAIN I LOVE YOU

- still confused here ;(