SET DASHBOARD IN BACKEND
At first you have to create your Ext-configuration with JavaScript. For more information look at ExtJS
Integration=>Quick Start.
Don't forget to add your used controller to your Acl.php.
The important step is this:
There is a global JavaScript variable called "Welcome" which contains an Ext-configuration of a panel to show in backend at /admin. (That's normally a box with your web-name and the Kwf Version) Just asign Welcome your dashboard variable.
For example you did the Quick-Start you have to add this line at the end of your JS file:
Welcome = Example.Foo;