The wide receiver job is what?

i have played wide receiver for 3 yrs now i am good but i need to know some things. i have caught a total of 51 touchdowns in the 3 yrs and i have a record for penaltys. wen the runningback was coming on my side i had to block but when i blocked they called holding on me. i got 13 penalties that whole game for holding can somebody tell me how to block without lettin da defense back getting to the RB. and on kickoff returns i hav only scored twice i need to work on speed can somebody tell me some workouts that involve speed increase