Get a first overview of Flow and a working example within 15 minutes with the Flow Quickstart or take the time and work through the Definitive Guide to Flow. More documentation is linked from the documentation library over at the Neos website.
If you get stuck, never hesitate to look behind the scenes and check how the internals of Flow work by diving into the API documentation.
Last but not least live sessions are an invaluable source of information. Quite some slides are available on Speaker Deck and on SlideShare.
The Neos project offer various resources to support you. Head over to the Support page on the Neos website to learn more.