Replacing Old Site With New One

Hi!

I am currently working on a website for somebody, with their current website sitting at “domain.com”. I want to upload the new one to “domain.com” through Yahoo’s FTP and hosting and replace the old one. I had the new website temporarily sitting at “domain.com/blog” until it was done, and now it is. This is my first time doing this, and I would like to safely transfer everything without having much downtime for the company online.

Thanks!