Updating a website

Hello,
I am a new user to Dreamweaver so I apologize if this is a really obvious
question:
I thought that when I PUT files from my computer on to the server after
changing them the website would be updated, but when I visited the site after
putting the files on the server the site looked the same as it did before. What
do I need to do to make changes visible (from more than just my computer)??

I'm using Dreamweaver 8.