There are several resources for learning about HDF5. The HDF Group provides an on-line HDF5 tutorial, documentation, examples, and videos. There are also tutorials provided by other organizations that are very useful for learning about HDF5.
For a quick introduction to HDF5 see the following:
These tutorials and examples are available for learning about the HDF5 High Level APIs, tools, Parallel HDF5, and the HDF5-1.10 VDS and SWMR new features: