If you are referring to the door seal, it is pretty easy.
1. Remove the plastic tread on the door sill. This is held down with 3 spring clips. Use a plastic interior tool, or a plastic putty knife.

Here are the locations of the 3 spring clips on the back

2. Remove the old seal by pulling off. Take note of the direction of the seal, and the starting location ( shown above, and below ).

The direction of the seal should show which side is out, and which side is in, double check it, to make sure they did not send you a driver's side on accident.
Putting the new seal back on is easy, I just hit it on with the palm of my hand ( with a sail makers palm on that is, no more nerve damage for me ). Do not stretch the seal, it is almost a case of pushing it together tight ( opposite of stretching ) while putting it on. Any little bit of stretch, and you will have too much length, and the door might leak.
Make sure the seal is at least 60* while working on it ( pliable ), I did the R&R for a project when it was 80* out, and it went smooth.
Hope this is the item you were looking for.