You can only enter those details of the relevant England Census.
Click on Search, then Census & Electoral Rolls.
Then, from the list on the Right-Hand side, select 1851 UK Census Collection, or 1861 UK Census Collection.
Scroll down, and select 1851 England Census, or 1861 England Census.
Then the boxes for Piece Number (and Folio No, and Page No, which you should also have from TNA) become available, as well as some others.
Enter the street name in quotes (i.e. as "Vaughan Ter") in the Keyword box.