dont stop asking , otherwise we wont be able to teach you
since you worked with previous yjsg version the process is same
difference is that the files that were located in old template html folder are now inside the plugin
root/plugins/system/yjsg/includes/html folder if template is released after yjsg v2
root/plugins/system/yjsg/legacy/html for older ones
you would now just copy the extension folder you want to edit to your template html folder and do same thing you did before.
but this time when you update the template, the changes you made will stay there