helo, in reply to your quiry about hindu gods,
from what i have been told, there are apparently 333,000,000 gods.
but whats the purpose of all those gods?
well the supreme lord, is lord krishna. 'krishna' meaning all beutiful. maybe if you choose to research into the supreme lord you may discover more about krishna.
lord brahma is the creator of this universe, and lord visnu is the preserver, and lord shiva is the destroyer. don't ask me about the destroyer - shiva, i don't know.
many people see brahma as the supreme, but he is not.
brahma did create the universe, but brahma was created by krsna. brahma was born from krishna's navel. brahma may have created the universe, and may be in charge of it, but the universe is material, above the material universe, there is the spiritual world. which krishna is in charge of.
i read a story of krishna when he was on this planet, that brahma stole krishna's friends and cows, and so krishna expanded himself intohis friends and cows so that the families of the friends wouldn't know. when he did this brahma realised that krsna is the ultimate personality of godhead and offered him prayers.
here is the story on 2 pages,
http://www.krsnabook.com/ch13.html and
http://www.krsnabook.com/ch14.html
i couldn't understand why there were so many demigods and for what purposes, but here is how it was explained to me.
"just like you have the prime minister who is ultimatly in charge of the country, you also have his different ministers who are in charge of the different parts of the government, eg. health, transport, economy. in the same way krsna is in charge, but he doesnt need to do anything because the various demigods are put in charge of the different aspects of the material world, eg. laxsmi for money, ganesh for prosperity and so on. so these demigods only have limited power and are under krsna."
you may already know that hindu's believe in life after death, and where your next life depends on how you life this life or previous lifes, all linked to the soul. but the only way out of this cycle is to surrender to krishna.
i hope this has helped you a little, although i know that my explanations aren't very good.
also some links that may help you.
www.krishna.com
www.krishnasoc.com
http://www.iskcon.com/
(http://www.iskcon.com/about/parampara/srila_prabupada.html)
and also, if you are from the U.K
http://www.iskcon.org.uk/
hare krishna