I have a brand new 2008 crf 150f and have only rode it 3 times and i noticed a knocking sound coming from the motor when i give it throttle

First try to locate the area where the knocking is comming from,one method is to use a lenght of wood like a short section of broom handel .start the engine and put your ear to one end of the wood and move the wood around the engine untill the knocking is at its loudest . This will tell you the area where to problem is .Then seek advice from someone who knows about engines ,Being a new bike there should be no knocking ,so there is a big problem either with the bearings or somethings hitting something .