Installing default.php page

When I tried to do it I screwed everything up so help would be much appreciated.

I guess it’s also called a Splash page.

Maybe call the file index.php?

Ok, well do I have to change anything in the cpanel of wordpress? If I replace the index page it won’t screw everything up?

Ok, well I guess I can just upload my own index.htm page on the main directory but how should it be set under Options so when you go to the index page it is the splash page and the Blog goes to the /blog page?

I think you are looking for the functionality of home.php? check out https://codex.www.ads-software.com/Template_Hierarchy