SharePoint 2013 Workflow Tutorials

Getting started with SharePoint Server 2013 workflow

https://technet.microsoft.com/en-us/library/jj227177(v=office.15).aspx

Workflow actions quick reference (SharePoint 2013 Workflow platform)

https://msdn.microsoft.com/en-us/library/office/jj164026.aspx

SharePoint 2013 Workflow - Task Process Designer

https://www.youtube.com/watch?v=ji5wxt4fcKc

Developing SharePoint 2013 workflows with SharePoint Designer

https://www.youtube.com/watch?v=A75qEwSd2kE

SharePoint 2013 Approval Workflow With Dynamic Approvers

https://www.youtube.com/watch?v=Vhwz_OJkP8g

SharePoint Designer 2013 - Call Web Service Video External Version

https://www.youtube.com/watch?v=dW6g9WR2Y8o&index=3&list=PL66r0mRA8am80Qsp6tRM1L_cdY3hos8Q8