In order to access the Brilliant API your CP will generate keys for you. Once generated a store admin can access them via the Automations page for your store.
The Brilliant API expects a Basic Authorization Header containing a base64 encoded API Key and API Secret Key combined with a colon between them. For example:
API Key: abc123
Secret Key: efg456
Would be combined like so:
abc123:efg456
Then base64 encoded yielding:
YWJjMTIzOmVmZzQ1Ng==\n
Finally you can use the Base64 encoded string in an Authorization header like so
curl https://api.brilliantmade.com/v4/me -H "Authorization: Basic YWJjMTIzOmVmZzQ1Ng==\n"