Hi there, I'm not to Umbraco

I've read "Integrating uCommerce with a Payment Provider" but can't see how to actually set up a payment form, and what to do with the properties on the Payment object (e.g. to set its status to successful or failed)

I'm just trying to imlement the simplest possible one-step case (no pre-auth), without redirecting offsite.  Does anyone have an example project they can send?  Or is the more detailed documentation somewhere on the web that I'm not finding?

Thanks in advance