Do you mean the weave poles?
There are many different ways that people try. My instructor has a set that has x-pens around them so the dogs can only weave correctly through them. Then one person releases them at one end and the other person calls to them with a treat at the other. It doesn't take very long before they start eagerly racing into them. Now that they have started to build some muscle memory for the weaves we are starting to phase out the x-pens.
I know that they also make what some call "channel weaves" where some of the poles slide out further so they can be gradually moved in so the dog builds up to the weaving. I haven't used them so I don't really know how to describe them.