i want to know my biological father

my names are Ushi Abdallah am about to turn 23 on october 16th.
my whole life i have been raised by my mother and grandmother.
when i was a kid i always wanted to know who my biological father was but
never got the chance to find out.
but now am all grown up i really want to find out who he really is.
but i don't know where to start.
i remember when i was in the kindergarten we used to be told by our teacher
every student to bring their father's birth certificate and i remember going home and delivering the news to my mum n she will tell me, "go tell your teacher that your father is dead."
i wanna know who he is and not because i wanna ditch my mum, i really cant do that to my mum caz i luv her.
but i have questions to ask him. there are things that i want them clarified.
if anyone has any advice for me on my way forward i will really appreciate.