Hi, Thomas.
We don't provide support for custom client development and sending manual requests to our community (free) users, it's too broad and complex of a topic. I would suggest you to first try it out using a supported RP, like [mod_auth_openidc](https://gluu.org/docs/ce/3.1.2/integration/sswebapps/openidc-rp/), study [the spec](http://openid.net/specs/openid-connect-core-1_0.html) thoroughly and observe what is being sent over the wire. Only after that proceed to low-level stuff, like sending manual requests. You can also try to search this boards for examples of such requests provided in other tickets.