The main idea is to use both of the two most amazing tools in Pentaho: the CTools and Kettle (also known as Pentaho Data Integration). If you know how to build Kettle jobs and transformations and also know how to build a dashboard, you should be able to build a Pentaho plugin. If not, it's about time to learn. I can recommend you two books: https://www.packtpub.com/big-data-and-business-intelligence/pentaho-data-integration-beginners-guide-second-edition and https://www.packtpub.com/big-data-and-business-intelligence/pentaho-data-integration-4-cookbook.
If you didn't know Java code, it would be hard for you to create a plugin, but that's not the case anymore as you are able to do it without the need to write Java code. You can also create a CTools dashboard...