Who were the Sioux and what did they do in their everyday lives?
Since this is not my area of expertise, I searched Google under the key words "Sioux Indians" to get these possible sources:
http://www.newadvent.org/cathen/14017a.htm
(Broken Link Removed)
http://www.sonofthesouth.net/union-generals/sioux-indians/sioux-indians.htm
http://en.wikipedia.org/wiki/Sioux
http://www.americanindians.com/Sioux.htm
I hope this helps. Thanks for asking.
In addition to the excellent sites posted by PsyDAG, you may also find these sites useful for information about Sioux daily life.
http://members.aol.com/donnclass/sioux.html
http://www.nmnh.si.edu/naa/fletcher/acf_sept_16.htm