Hi
You can change the sidebar size from File templates/ja_biz/tpls/blocks/mainbody/one-sidebar-right.php
I am not sure which layout you are using , so that as an example i am giving you changes for /one-sidebar-right.php
You need to change the col-md size for main content and sidebar . Increase col-md-3 to 4 for sidebar and decrease from main content (col-md-9 to 8) . Total size of col would be 12
Screenshot : http://prntscr.com/aug0qo
For slideshow i am afraid it designed with full width container design style and does not have sidebar position , If you want to add new module position you can add it in the tpls/blocks/slideshow.php .
But it break the slideshow design .