To create a simple HTML page with the words "You are welcome" in the middle of the screen, we only need a single HTML file. Here is the content of the file:
index.html
```html
Welcome Page
You are welcome
```
In this file, we have a basic HTML structure with a `head` and `body` section. The `head` section contains the title of the page and a `style` tag for CSS. The CSS is used to center the text both vertically and horizontally in the middle of the screen. The `body` section contains a `h1` tag with the text "You are welcome".
This concludes a fully working implementation.