How to enter the site editing?
If your site is on WordPress, then in the browser line after the name of the site enter / wp-admin and you will be taken to the page to enter a password for administration. Maybe on other engines something like that, you can experiment.
From the beginning you need to go to the hosting where your site is located, then to the control panel of your site, and edit it there.
If the site is written in NTML, then simply copy it to the computer and edit it as necessary, then upload it to the server and that's it.
If the PHP will have to edit on the server.
Something like this, maybe there are other ways I don’t know about them.