SQL Server
KS.CRM supports MS-SQL Server since version 2005 or above. The latest version is recommended. The free Express version is enough. Large databases run faster on a non-free version of the SQL server. You should not install a SQL Server on a notebook. You may also use a SQL Server hosting service or you could use cloud services that provide a SQL Server, so that you can access your database from anywhere in the world.
Create database
Select the Program menu Tools|Create new database.
You will need a login on the SQL Server, which has sufficient rights to create databases and objects. You should normally be DBO (database owner) for this database.
Manage Users
In menu Extras|Manage Users you can create additional users or delete them if you have the rights to the database. Of course you can also use the SQL Server Management Studio.
A new database user should open menu Extras|Edit my profile and enter at least his first and last name. Many program functions show this user name later on.
Database Backups
Use the SQL Server Management Studio (SSMS) to make a backup plan. This requires good administration skills for the SQL Server.