--Set Request Headers
apex_web_service.g_request_headers(1).name := 'Authorization';
apex_web_service.g_request_headers(1).value := '[MY API TOKEN]';
apex_web_service.g_request_headers(2).name := 'Content-Type';
apex_web_service.g_request_headers(2).value := 'application/json';
apex_web_service.g_request_headers(3).name := 'Content-Length';
apex_web_service.g_request_headers(3).value := '[CONTENT LENGTH IN BYTES OF REQUEST BODY]';
l_lcResult := apex_web_service.make_rest_request(p_url => 'MY API URL'
,p_http_method => 'POST'
,p_body => 'REQUEST BODY IN JSON FORMAT');