Redirect

I want my site to show up without the sidebar like this :

https://www.rhastings.net/archives/2005/02/19/my-first-wordpress-15-theme/

I am installing WP into a subdirectory on my site https://www.mydomain.com/wp/index.php
I would like to have anyone that goes to my site to go directly to the page without having to see the sidebar “and” the domain name in the browser address bar ( so I don’t have a long string). I only know a tiny bit of PHP.

I guess that I need an index PHP in the root that (somehow) redirects.
Thanks in advance.
Christopher