There are a few tutorials available for setting up Appit and building workflows.

Here is a link to the site:

http://help.k2.com/helppages/K2ForSharePointUserGuide1.0/default.htm

Open the "Learn" menu on the left and there are five different tutorials you can run through. I suggest starting with the "Hello world" tutorial. It is the simplest of the five. Once you are comfortable with that, then continue through the other four. They increase in functionality and difficulty.

Thanks. They are a great help :)

Couple of links that I found very relevant 

• K2 Appit for Sharepoint
• Introduction to K2 (PDF)