Internally, the communication with the adapter is implemented by sending data blocks to and from the adapter. These blocks of data represent commands, responses and events.
You do not need to understand all these data structures to write your application. Most of functionality is encapsulated in the regular C-style functions (for example, DlnOpenUsbDevice(), DlnI2cMasterTransfer(), etc.). All you need to do is to call these functions and the rest of the work will be done by the dln.dll shared library and the device driver.
If you want to benefit from the event-driven interface, or to optimize the speed of the data transfer between your application and the adapter by using asynchronous interface, you can return and read the corresponding chapters later.