There are times when you may want to create custom forms from scratch and there may be some confusion on how to do this. This documentation supplies some information that is quite useful but please note that this document also has information regarding K2 Studio which is not applicable to K2 Appit for SharePoint. 

Link to document:

http://help.k2.com/HelpPages/K2smartformsUserGuide1.0.7/default.htm#SF_-_FormDesigner_Wizard_Navigation.html#tracksearch=form layout