The 1911 census was no different to any other census (post 1840). The enumerator left a census form at a household, and somebody in the household filled it in. The enumerator then transferred the data from each form in schedule order, into his book. The enumerators rarely helped householders in the completion of the forms.
What makes the 1911 census different is that the actual schedule forms were stored, as well as the enumerator returns. In all the preceding censuses, the schedules didn't survive once they had been transferred into the books.