How do I get it over and into my server to be displayed for all the world to see?
As your question has 2 parts, I will try to answer them both. Firstly, the "How do I get it over" part. You just need to install ssh server program on your ubuntu box and then ssh from your windows 7 by using putty. Putty is better for administrating your ubuntu server, but to transfer files winscp is better with a nice GUI and drag&drop operation. It's basically windows version of linux program called 'scp' (Secure CoPy). Either way, you will need ssh.
To install ssh, execute the following commands.
sudo apt-get update
sudo apt-get install openssh-server
And to be able to open localhost on your browser, you need to install apache, or any other software for that matter.
sudo apt-get update
sudo apt-get install apache2
Now, you can have the HTML/CSS documents on the ubuntu server. And you can view the "It works!" page on localhost with browser.
"To be displayed for all the world to see?" As for this part of the question, I can only give you a brief guide, as I don't have experience on web development. You will need to buy a domain name (or get a free one), and hosting space (or you can use your ubuntu box as server). Here's a basic tutorial from digitalocean. You can get more information by searching on google.