We did a few code samples on how to authenticate to ClearID. You can find more details about the Authentication in this article

For example about the different REST calls, we really recommend using the swagger interactive documentation to test out the different API calls: How to call a REST API via Swagger UI

C# Sample

This sample shows how to use Microsoft library to create the assertion token and authenticate to ClearID.
Download the complete C# sample

Java sample

This sample shows how to create the assertion token and authenticate to ClearID in Java.
Download the complete Java sample

Javascript sample

We created a sample that shows how to authenticate in Javascript. The complete code is posted on CodeSandbox.io

You can test it our by forking the sample and update the JSON file with the one download from your account. See JSON file section in this article