Wynona 's instructions a few posts back. Otherwise, you should wait for it to be released to the general public, and then the ISOs will be available for download from MS.
Activate Windows 10 - Windows 10 Forums
I have also posted about my own tests regarding this matter: Announcing Windows 10 Insider Preview Build 10565 - Page 18 - Windows 10 Forums
If you look at my post, you'll see that there was no second paragraph quoted (because at that time there was none). Then look at your post and there's a second paragraph quoted (must have been added later). That's what I was talking about.
However, if I'm not mistaken, you can upgrade from Windows 7 or 8.1 by . . . drum roll please . . . here are instructions for a clean install without upgrading:
Clean Install Windows 10 Directly without having to Upgrade First - Windows 10 Forums
Thanks guys, I appreciate the help and info!