We would like to change the minor changes in the content page and webform design, dont know how to access the file. How to get the FTP files from my site need to add custom css file. Any help please.
I would recomment reading up on how to customize CiviCRM here: https://docs.civicrm.org/dev/en/latest/ and here: https://docs.civicrm.org/sysadmin/en/latest/customize/extensions/
That should answer your question and also allow you to do the customizations in a recommended and structured way.
If you would like a more specific answer it will help us all ot help you if you tell us a little more about what you want to change for what reason, what version of CiviCRM you are using and what CMS.