surveys for free zp.

Hi, i was just wondering about the surveys for free zp, well i did 2 surveys 1 for 3500 zp and the other for 1000zp. I was wondering if i could spend that in item mall, i do not know how to use it. and how it says confirmation on 3rd page how do i do that. I won't like it if i had to spend money on surveys then get nothing out of it. It would be good if a GM could help me with this thanks.