Downloading' means getting information. Your web designers can take care of that if you wish. Once your site has been uploaded, it needs to be tested and tuned-up accordingly. This stage has to have your cooperation as only you can say if your are happy with your site. It is also useful to have other people to try your site out and notice their reactions and suggestions.
Nobody knows it exists.
When people surf the web, they usually 'search' for something specific. You want to be found when they are looking for something you offer. Usually the best 'search engines' automatically will eventually discover your site and put it into their database. They do that through programs called 'crawlers', or 'robots, or 'spiders', and other things. However, this may take time, as there are thousands of new pages and sites everyday.