I am trying to add a splash page before the index.php

I understood this to be done by adding this to the htaccess file:

DirectoryIndex index.html index.php

But I put that in there and it does not do anything. Is my assumption that I 1) modify the htaccess.txt file in the same directory as my index.php and index.html file 2) add line of code 3)rename to .htaccess

I am not sure what I am missing?

Thanks