New website not showing up

This is my first WP website and I’m not the most tech-y person so bear with me. I have a current website that I’m replacing with a WP site.
I got on my web host and they had a one-step WP install. That worked fine. It then asked me where I wanted the WP installed. The options were http://mywebsite.com or http://www.mywebsite.com Since I’m creating a totally new website in WP, not just a blog, I chose the second option. I was able to load the theme I bought and everything seemed to be fine. I logged onto WP, everything looks just like what I”m seeing on the quickstart PDF but, when I go to look at my website, the old website is still there. Any ideas? Do I just need to remove all the old info? If I take down the old index page will WP show up? Or am I missing something else altogether?