The API docs refer to an oauth security token (also called an access token) that needs to accompany each API request.
Your oauth security token (access token) will look like the following...
Note that it includes the word "bearer" followed by a space followed by the access token.
The following article explains the exact anatomy of a request/response and how to use your oath security token.
To verify it's all working, follow the instructions below:
Step 1: Go to the live test website located at: https://api.dsco.io/docs/v2/#!/hello/helloWorld
Step 2: Paste your oauth security token in the field in the top right and hit the Enter key on your keyboard. Remember to include the word "bearer" at the beginning.
Step 3: Click on the bold "hello" link on the right so that it expands.
Step 4: Click on the blue "Get" button so that it expands.
Step 5: Click on the Try it out! button down below.
Step 6: You should now see a successful request/response.