An inference is a conclusion reached on the basis of evidence and reasoning.
INFER FROM TEXTS
"They told me about my biological mother, Heather, who was 17 when I was born. Her mom kicked her out, and her boyfriend told her..."
Based on these sentences I can infer that the author was adopted because someone, probably her adopted parents, told her about her real, or biological, mother.
"Sweat pounded down my sweltering forehead, my muscles burned and every bone in my body screamed at me to stop, slow down. But my mind..."
From this sentence I can infer that the character is exhausted from running. I infer this because the character is sweating, his/her muscles are hurting from being used, and he must be moving somewhere since he wants to slow down.
"Like love is only for responsible adults. Well let me say something right here and right now: By the time you are thirteen, you have probably been in love. There I said it. Now people can argue about it."
The author is telling the reader that kids do know love, not only adults, and therefor I infer that the author has probably been in love as a teenager.
INFER FROM PICTURES
From this picture I can infer that the boy does not like what he is eating because he looks like he is pouting with his head resting on his hand. Usually if someone rests their head on their hand it means that they are bored or unwilling to do something.
I can infer that the mom is helping the two kids with their homework. I infer this because she is pointing to things on the paper as if she is teaching the kids how to do something. There are also text books out that look like homework.
I infer that the lady loves to garden because she is putting plants into her really nice garden that doesn't have any weeds.