Ancestry.co.uk has an index to Scottish censuses, but to see a scan of the actual entry you need to look at ScotlandsPeople online. There won't be much extra information in 1841 when relationships weren't given, and ages rounded, but William's occupation should be there. The index has:

Name: John Bremner
Age: 10
Estimated birth year: abt 1831
Gender: Male
Where born: Banffshire, Scotland (this may be an assumption by Ancestry).
Civil parish: Boyndie
County: Banffshire
Address: Cairntown
Parish Number: 149
Household Members: Name Age
William Bremner 60
John Bremner 10
Ann Bremner 20
William Shand 5

The IGI has an extracted entry for the marriage of William Bremner & Ann CHEYNE on 10 MAY 1828 Banff, Banff, Scotland. This is on LDS film no. 0990816-8 which you can order to view for a small fee at any Family History Centre worldwide. See in phone book under Church of Jesus Christ of Latter-Day Saints.

John's birth and bapt entry is on LDS film no.0990818: Parish registers for Banff, 1620-1854 Church of Scotland. Parish Church of Banff (Banffshire). You may find family burials there as well. The description of the film has: "Baptisms and marriages, v. 9, 1820-1826; Burials, 1820-1854; Baptisms and marriages, v. 10, 1826-1854. (Preferred film for viewing. Use this before ordering the other filming.)" Although they have given the earlier number for the marriage, I'd check this film first and only order the other one if the marriage isn't there.

Sue