This is the "Hello World" of Hyperledger Composer samples.
This sample defines a business network composed of a single asset type (SampleAsset), a single participant type (SampleParticipant), a single transaction type (SampleTransaction), and a single event type (SampleEvent).
SampleAssets are owned by a SampleParticipant, and the value property on a SampleAsset can be modified by submitting a SampleTransaction. The SampleTransaction emits a SampleEvent that notifies applications of the old and new values for each modified SampleAsset.
To get started inside Hyperledger Composer you can click the Test tab and create instances of SampleAsset and SampleParticipant. Make sure that the owner property on the SampleAsset refers to a SampleParticipant that you have created.
You can then submit a SampleTransaction, making sure that the asset property refers to an asset that you created earlier. After the transaction has been processed you should see that the value property on the asset has been modified, and that a SampleEvent has been emitted.
The logic for updating the asset when a SampleTransaction is processed is written in sample.js.
Don't forget that you can import more advanced samples into Hyperledger Composer using the Import/Replace button.
Have fun learning Hyperledger Composer!