Just off the top of my head, I haven't tested this or anything, but try something like
SELECT COUNT(*) "OCCURRENCES", tbluser.fldloginname "Card Number", tbluser.fldfirstname "First Name", tbluser.fldlastname "Surname"
FROM viewreservation join tbluser on tbluser.fldID = viewreservation.flduserID
WHERE viewreservation.fldstarttime > @startdate and fldstarttime < dateadd(day,1,@enddate) and viewreservation.flddeleted = 0
ORDER BY tbluser.fldloginname GROUP BY tbluser.fldloginname