Your adapter must convert between the data format(s) appropriate for your application and the representation of rows as defined by the SDK you are using.
You should be familiar with your application's data formats, and you should be able to extract the data into rows and fields.
If your adapter is an input adapter, then once you receive a row of data, you call SDK functions to construct a new row, set its timestamp, set its fields, and publish it to the stream.
If your adapter is an output adapter, then once you receive a row of data, you call SDK functions to read fields from that row and send the information to your data destination.