What does it take to be social-friendly?

I don't socialize much at all on a daily/weekly/monthly basis. I'm very sheltered and appear unfriendly....bc I don't smile and I'm very sensitive (Take things very seriously). l don't hold eye contact wt ppl much...i look elsewhere but ppl's eyes. I feel like im not normal and need some extra help to get over this. I've once heard some1 say..."wa'ts wrong wt her" across the table and im scared to hold eye contact the most wt guys...bc i've been hurt by a male (physically when i was little). Ppl dont' like me...im moody so i greet ppl when i feel like it, it seems as an unfriendly gesture and im just not sure whether i need therapy or somethin or will this somehow change on its own.