You can begin uploading to your account now by using an FTP Client or cPanel's File Manager.
If you are using an FTP client, put in your site's IP address under the "FTP address" field. Use the username and password sent to you in your welcome email. FTP always runs on Port 21.
Once your FTP is connected, go into the "public_html" folder and begin uploading your site. To replace the default place holder page, you must upload an index.html in all lowercase lettering or delete the page and replace it with your own index page.
Please note that by default, you do not have an email address setup with HostGator. You will need to configure this yourself in cPanel (link below).
Step 2: Note These Useful Links
"Before propagation" as it is defined below is the point between when you sign up and when the changes to your name servers take effect (usually about 24 hours after you change your name servers).
"After propagation" is once your site is up and running normally.
During propagation you should use the "Before propagation" format.
Be sure to replace the information in red with the information from your welcome email.