You can see what I'm talking about in the screenshot below.
Basically, I have a subdomain (i.e. subdomain.website.com) and all I want on it is a single HTML document to display. The HTML document is titled home.php in the image but it should be home.html, which I'll change later.
When I open subscribe.website.com in my browser, I'm presented with the 2nd image, and have to click on the document link to display it. Is there a way to set it up so that when I go to subscribe.website.com, home.html document loads automatically?

What you are trying to achieve can be done in multiple ways:
index.htmlThis is because most web servers are configured by default to server somedefault document's, of whichindex.htmlis one, and so isindex.phpif you fancy it.your-page-name.extto that list ofdefault document's. But the way to do this is server dependent. You seem to have a Linux host. In which case, you can use the solution provided by @Ethanh by addingDirectoryIndex home.htmlto your.htaccessfile. If this doesn't work, there is the possibility that your host doesn't allow you to edit.htaccessfiles. In this case, you will have to contact your web host.default documentlist ofIIS