Authorization

Hi!

I am evaluating the free plugin for a specific development requirement I have. I am trying to access a remote API but I get the following back:

{“error”:”Your API key is invalid”}

Where do I specify the authorization token for the API call?

In PHP using cURL I can do it this way:
$headers[] = ‘X-Authorization: xxxxxt1fhttsdewqppn1oxrffds’;

Where in the plugin can I pass the value xxxxxt1fhttsdewqppn1oxrffds?

Thanks!