I don't know...do you?

I am 35weeks pregnant, and I am 1 cm dilated and 40% effaced. Does this mean I had to have a contraction to dilate? Well, I mean, to dilate and efface don't you have to contract or don't you? I am wondering because I don't kow what they feel like or bh contractions. My stomach hurts in different ways all the time so I don't know what it feels like or when I would have had a contraction.