Creating forms in Orchard Core CMS with the Form Part and Form Widget is very easy, but the Workflow to simply validate form fields server-side is way too complex for simple forms. The Contact form in the Coming Soon Theme is a great example.
Workflow in Orchard Core
Orchard Core Workflow tutorials, tips, and sample code. Teaching Orchard Core Developers how to use Workflow in Orchard Core using Orchard Core tutorials and examples.