As a newer to SDK and C#, it took me a number of days to understand the document:
Sage ACT! 2013 Architecture Reference.pdf (within SDK package)
This document gives a brief summary, but it is definitely the most enssential document. The sample code (p18, p17) in it is a key to start our coding.
The concept of "Managers" was annoying me. It is like "Act.Framework.Contacts/Histories". We can declare it like:
ActFramework actApp = new ActFramework(); actApp.LogOn("C:/****/act.pad", "name", "password");
ContactManage conMgr = actApp.Contacts; // use conMgr (like a table in database) to get contact properties.
"Entity" can be "Contact", "Company", "Group", "History" and so on (like a row in database). With ContactList, we can go thought every Contact entity.
DBFieldDescriptor helps to get properties (like a column in database).