replacing fuel injectors on 02 silverado

[salrod00]

ok well now im down to this. i replaced the coolant sensor and all the spark plugs and wires to it. now i still have a miss fire on cylinder one which is the fuel injector. i already bought the injector and am ready to switch it out. i have a V6 engine and it seems that the injectors are underneath a plastic case. i dont see no outside fuel rails. how hard are these to switch out,. i just need to replace one only., any help or advice will be great .