Small correction: Sage do not actually own Quickbooks . It is owned by a competitor - Intuit. However, many third party applications integrate perfectly well with Quickbooks.
There are a number of Quickbooks user-forum type sites on the net. I researched the product a while back (fine product, but for reasons not relevant here I didn't buy it) and I can remember that there were lots of good info resources, but I am afraid it is too long ago for me to be able to remember specifics - a google search will throw up plenty I am sure.