Sure. Welcome to the Mendix world! For us to be able to help you out, we need more information then this. Tell us more about what registration you are talking about and which API you are trying to consume.
Nevertheless maybe you are already well on your way if you check this doc: https://docs.mendix.com/refguide/consumed-rest-services#1-rest
I looked at this section of the documentation. And even watched the video. But I could not do it the same way as in the video, it uses a GET request, and data input via the Input method in my studio version works somehow differently. I couldn't figure it out. Could you provide a finished example?
I need to make a registration form with two String fields: login and password.
something like this should look like my request after filling out the form and clicking the "Register" button: