You could start here
http://www.bbc.co.uk/history/familyhistory/
I found that the best way to start was to ask older relatives for any details they could give me, when their parents were born, where, any aunts, uncles, could they remember their grandparents etc. Then work backwards, starting with your parents or granparents. Birth certificates give the mothers maiden name, marriage certificates give the fathers name of both the bride and groom. The census on line is great, once you have found your family on their you can usually track them back through the years. Good luck.
Oh - one other thing, under the history category there is a genealogy section, you may get more positive responses on there.