The authentication to the SEOResearch API works by, attaching your apiKey and secret as GET parameters for each request to the API you make.
In order to obtain said credentials you have to register for the SEOResearch API.
When your registration is complete and you login to the dashboard, at the top of the screen you will see your api credentials.
Another important piece of information is the Quota. That is how many requests per month is your account allowed. Free accounts have a quota of 50 requests per month, you can check our paid plans here.