Chevrolet Impala Fuel Injector Replace/Remove

Where Are The Ful Injectors Located In The Motor,and Can An Amuture Mechanic Like Me Be Able To Remove Them And Replace Them . I Have A...

I Was Replacing An O-ring On A Fuel Injector And The Little Plastic Cone I Used To Slip The New O-ring On With Fell Into The Injector Tube...