where I can find a free site for census for 1901
There is no free online access to the original images of the 1901 census of Scotland.
or do a look up for me
The 1901 census is only available online in the form of transcriptions, which may contain errors and do not always include all the information in the original. They can also contain misinformation that is not in the original, such as a (mis)calculated year of birth.
The 1901 transcriptions are, generally, only available on subscription sites so they are not exactly 'free'. The exception is
www.familysearch.org but you cannot look up a whole household there - only individuals.
So whatever information people are kind enough to give you, you still need to plan to check that information against the original image on
www.scotlandspeople.gov.uk.
