Schemes and Forms allow you, the local administrator, to control what kinds of pages can be created on your Swiki. To edit schemes and forms, use the forms address of a page; for this page, that would be http:/refs/13.forms. In order to access that address, you will need to enter the user:password adminID that can be changed from the AdminTool (http:/admin/settings?book=refs). The default is admin:password.
Every page has a scheme that determines what kind of pages (i.e. forms) can be created from it and what scheme will be used by these pages. This page uses the "example" scheme. It allows for pages created from this page to be either blank text or blank (Squeak) projects. To test out how this works, try creating a new page from this page. The "example" scheme also has, as its children scheme, the "default" scheme, which is used by the first page of each Swiki. That means all (both text and project) pages created from this page will use the "default" scheme.
There are two types of forms: text forms and project forms. Text forms allow pages using them to have multiple edit fields. Check out Je77's Survey page, which uses the "survey" text form. Project forms are a similar concept for Squeak plug-in based pages. You, the local administrator, can upload a Squeak project that will be used as the starting point for any pages created using that form.
In either case, forms allow you to guide usage of the Swiki.