Changing Stage step on a ribbon button click

USIING CRM 2015

I have changed out of the box Process to be something like this

Propose > Evaluation > Close

In  my design user will only get to click on the "Qualify" and "Disqualify" button in the Evaluation stage.  I want the progress of the flow (the flag) to automatically move the close stage once either of the button is pressed.

Similarly - I want the progress of the flow (the flag) to automatically move to the Evaluation stage when "Reactivation" button is pressed from the button. 

Could you kindly tell me  - what would be the easiest way (code\configuration) to achieve this?

Thanks,

Hasib

Hasibur Rahman