Authentication on external ql

I’m trying to connect my frontend to my backend. The backend with its query is on another server and therefore needs authentication. My frontend is just a Next.js framework hosted on a CDN. Inside Next.js I want to fetch the data with Apollo. How can I send the authentication, consisting of username and password, to my backend? I use Kirby QL for my backend: GitHub - getkirby/kql: Kirby's Query Language API combines the flexibility of Kirby's data structures, the power of GraphQL and the simplicity of REST.

Thanks in advance