One of my favorite exercises is the BB Good Morning. Both the bent knee and straight leg version will work the hamstrings. Below is a video showing a bent legged good morning.
Done with poor form you can injure yourself very quickly. Here is a good way to start. Get yourself a broom stick. Hold it behind your back with the top of the stick touching the back of your head and the bottom touching your tail bone. Feet should be a about shoulder width or a little wider, find a comfortable stance. With the stick behind you, touching back of head and tail bone, push hips back, forcing you to bend forward. Take it slow as you are learning and make sure that the stick remains in contact with the back of your head and tail bone the entire bend. Once you get the movement down, move to an oly bar.
There is some difference on the opinion of bar position preference. I prefer a low bar position, as IMHO this does not put as much stress on the lower back. Work with just the bar and then begin to increase weight slowly. Don't be in a hurry to increase weight, take your time, you will be rewarded for your patience.
I apologize for video quality, There are few good videos of the good morning on youtube.