i was told in the apple store when I bought my new 16g i pad (the one without a data plan) that there was a way to hook it to my I phone so that my I pad had wireless ability when my kids were on the road with me. How do i do this???

I just bought a new 16G I Pad for my daughter. I was told I did not need the data plan becuase she would usually be using it where there would be wireless available. When I asked about when we were traveling, the rep told me that I could hook up the I Pad to my I phone and she could piggy back on my wireless. I just opened the box and don't see how the accessories fit to make that happen. Help!!!