英语分词修饰前面的名词时中间加逗号表示什么含义？

英语分词修饰前面的名词时中间加逗号表示什么含义？
例如While stepping back was difficult for me,it was certainly a good first step that I will quickly follow with more steps,putting myself far enough away to give her room but close enough to help if asked.中putting前面加逗号是什么意思？求高手解答谢谢