Uploading a website : I'm uploading a website and there is the previous website there from before?

When i upload the new website nothing changes. Do i need to delete the old website or am I doing something wrong??Uploading a website : I'm uploading a website and there is the previous website there from before?backup the previous website files all and delete it and upload the new one since there are some important files which are only 1 per domain so they need to be changed to new unless they r replaced ya new domain won't work.