1- Get API Key          2- Check Scenarios       3 - Read API Reference

Once you have gone through the above then you can code, test and deploy.  
   
Code: SigningHub uses REST architectural style APIs and hence you can use any language to integrate e.g. PHP, Node.js, Django, Java etc. 
Test & Deploy: You can either use the cloud hosted SigningHub or your on-premise deployed for testing and deployment
Important Changes from Version 6.5.x
SigningHub now operates on a concept of packages.  This major change was introduced to enable the preparation, sharing, and workflow of multiple documents in a single operation.  Previously, each document was a unique resource with SigningHub and managed accordingly.  With version 7 a whole new infrastructure has been put in place to turn this concept on its head.  Now every interaction concerning documents is focused upon packages.  Even for a single document: a single document is treated as a package containing one document.

Integration with SigningHub operates at a a package level.  All operations involving document preparation and sharing rely on a package.  Creating a package is the first step in the process for any model of integration.  See the Add Package for complete details.  Once a package is ready documents can be uploaded to it, or pulled from other sources such as cloud drives or personal or enterprise document libraries.

Further enhancements are the ability to add signature fields via coordinates and page number as opposed to the previous implementation that relied on document templates (document templates are created manually via SigningHub desktop), customise signature appearance for both mobile and desktop, and even upload visible signature appearances in real time.  With over 100 new APIs the functionality available is almost unrecognisable from previous versions.