The front page has general information on the census and on life in Ireland in 1911, but the search form is one link down. You can search the census by a variety of factors, including first and last name, street, and approximate age in 1911 (plus or minus five years.)
I did a search for John Field (I’m kind of on a John Field kick at the moment) and got 38 results. Results are presented in a table that includes name, county, age, and sex. Click on the surname or first name and you’ll get a list of all the people in that household along with their ages and gender. Beneath that you’ll get a list of the other forms associated with this household (for instance, household return, outbuilding return, etc.)
The unusual thing about this census, though, is there’s no built-in viewer for these additional documents. They’re PDF, so you’ll have to use your browser’s PDF viewer or download the files. I downloaded a household file just to see what was in it. If you’ve ever done genealogy research before it’ll look very familiar as a census file. Information include the names of folks in the household, their relationship to the head of the household, and so on. Other information, less usual to a census form in my experience, includes the religion of the people in the household, whether they can read or write, and their licensed professions.