Hi,
JA Focus is built with Bootstrap grid system, you can change the width by reducing/increasing the number of grid via class.
In this case, you open the file: root/templates/ja_focus/tpls/blocks/mainbody/one-sidebar-right.php
You will see classes like: col-sm-8, col-sm-4: http://prntscr.com/ib7dul , then you can change this value to your desired value but make sure that the total grid is always equal to 12. For example: from col-sm-4 to col-sm-3 and col-sm-8 to col-sm-9
Check out this documetation for more info about grid system of Bootstrap: https://getbootstrap.com/docs/3.3/css/#grid
Regards