How to start workflow with from button which is a custom list on additem template( default save and cancel avaliable i need another one submit)

Hi  i have a share point designer workflow which is  manual checked item which have two buttonsstart and cancel , i have a custom list in this list when we click additem default which havesave and cancel button, here i need another button calledsubmit .when we click submit button workflow have to be start (workflow start button event will  fire here) and list fields need to be save here.   can anybody please help me.