The core integration path is three steps: authenticate, register a customer, then raise a callout. This page explains what each step is for — follow the links into the API Reference for the exact request and response shapes.
Exchange your server credentials for a bearer token, then send it on every request. Start with the Authentication guide, or go straight to the reference: Exchange credentials for a token.
Create the protected end user under your customer source. The customer you create is the subject of every callout and subscription that follows. Reference: Create a customer.
Create an emergency-response request for that customer with a response type and a location. From here the callout moves through its lifecycle — see the Callout lifecycle guide. Reference: Raise a customer callout.