dog distractions

i have adog that im training for agility
he is cross bred, can he compete?
he is quiet anti-social towards other mdogs and human outside this house
he gets distracted easily and cant relax outside the yard...how can i train him so that i can let him off his leash in a competition and trust that he's not going to lunge at the crowd?

desensitization, socialization, and focus activies.