Application Server integration trough HTTP API

Hello, Im really new in HTTP procolos and API’s
In simple terms I need to be capable of forwarding the data incoming to the gateway to an external server (thingspeak, thingsboard not locally hosted, etc), I need to learn to manage all the tools that chirpstack provide me to achieve this goals.
I understand that I neet to learn a loot, where can I start learning all the things needed?