Trying to install wordpress website overtop of existing website – help!!

Hi there,
I really hope you can help me!
I had a webpage, and I wanted to change it, so I have downloaded wordpress to the main domain, but the wordpress site is not appearing on the website. I have been trying to figure out how to remove the existing homepage, using cpanel, but not having much luck. In the file manager I moved the index page from the public folder to the home folder… Anyway, you can see that I really have no idea what I’m doing, so any help would be much appreciated! Can anyone tell me how to remove the webpage I had there, and how to make the wordpress one appear?

One more really dumb question – when I downloaded wordpress and it asked for the domain, I didn’t include the “www.” bit – was I supposed to include this? Also, I left the directory empty..

Cheers
GB