How I can enable password changing feature for site's users in SharePoint 2013, so that each user can changed him/her password?
here is no OOB web part or application page avaliable for user self changing the password in AD in SharePoint, you need to create a SharePoint web part programmatically to let users reset their password in AD.
Their are two options
- Create your own webpart and let the user to change their password. check these two posts.links or How to change active directory password using Code?
- Or you can use the 3rd party option. free from codeplex or Bamboo solution
Also you can consider solution from VirtoSoftware Password Changing (30-days free).