tracey1 on Family Tree Circles

Hi all
my name is Tracey Bihell married Renyard
I'm trying to find my dad's biological father, it's really hard as my dad has passed so has my nan .dad knew that the man that raised him was not his biological father,the story as i was told is when his bio dad was dying my nan said to dad this is your last chance to meet him do you want to , dad said no that he didnt want him when nan was pregnant and that he only had one father and that was who raised him. what i have been told true or not unknown,dads bio was friends with the dad who raised dad and because the bio dad didn't want anything to do with my nan at the time his friend pop as I know married and raised my dad as his own.i did a DNA test as my dad has passed as well all I know is

dad was born 1945 in kurri kurri nsw
my pop as I knew was in the army may be the friend was too ?
i don't understand how to read the DNA matches
dad was one of 5 .4 to the pop I knew but one is from my pop and my nan's sister and of course dad to another man unknown

i there is anyone who can help guide meon how to match dna results to maybe find a relative of my dads bio family

thank

hi looking for all info on my family names