I am fairly new to cycling so forgive me if I sound ignorant. I have a Specialized Allez with a triple chainring. The hoods say Shimano Sora flightdeck triple. The problem I'm having is shifting from the middle chainring to the small chainring or from the small chainring to the middle chainring. I just get this grinding sound from my chain. It will not shift smoothly. I have to press and hold the shift leaver to shift up and even then I may have to try it two or three times. I am pushing the leaver all the way over. Or if I push the button to shift down the chain just grinds. I have to shift my rear derailer in order to get it to move in the front. It doesn't matter what cog my chain is on it the back, it still won't shift smoothly. What do I need to do to fix this? Please remember that I am new to all of this so I need simple, detailed instructions. Thanks.