Hi,
you could create/select/delete a new document using API. The API example you could find here:
Creating a new documentIf you mean that you would like to get a list of fields related to some document type, here is an example:
DataClassInfo classInfo = DataClassInfoProvider.GetDataClass(ClassId);
FormInfo formInfo = new FormInfo(classInfo.ClassFormDefinition);
The created document is a standard one and you can display it the same way as documents created in the UI in the CMS Desk.
Best regards,
Ivana Tomanickova