The dotnet command is used to build and run the .NET project. In order to run the producer, use the dotnet run command from the producer directory: 
cd producer
dotnet run
You should see output resembling this: 
Produced event to topic purchases: key = sgarcia    value = alarm clock
Produced event to topic purchases: key = jsmith     value = alarm clock
Produced event to topic purchases: key = sgarcia    value = book
Produced event to topic purchases: key = htanaka    value = batteries
Produced event to topic purchases: key = htanaka    value = book
Produced event to topic purchases: key = eabara     value = batteries
Produced event to topic purchases: key = jbernard   value = batteries
Produced event to topic purchases: key = eabara     value = t-shirts
Produced event to topic purchases: key = jbernard   value = t-shirts
Produced event to topic purchases: key = eabara     value = t-shirts
10 messages were produced to topic purchases