How do gain weight?????????

iam oober skinny and cant gian no freakin wieght...but i eat constantlly i heard u can lift weights to biuld musle and i did that and i kinda made me skinnier uhg i was was sore all over too :( maybe any food thats good for gianing wieght or exterise that wont make me skinnier or somthing that makes you fat! anything thank oh im a girl btw