How do I integrate a courier service?

Hello, how can I solve the problem of integrating a Hungarian courier service into the starting webshop? Eg Gls Dhl or foxpost.

That's a yellow card for hijacking another topic with an off topic question.

Have you seen this article?
https://wiki.litecart.net/how_to_create_a_shipping_module

Sorry for my inattention, the warning is legitimate.