You ARE on the right track... Success is near
"does the "yournumber@vzwpix" actually go in the "To" field in your email?
Example with a phone number I made up TO:
3159991234@vzwpix.com goes in the "To" field in your email?
YES... Perfect...
" How does it know to send it to my phone? I haven't entered a phone number anywhere in my email."
You have your phone number in the TO: field already....
"When I tried to send it as an attachment, I went into My Computer" <---- YES again.....
You have to figure out were you saved the Ringtone to on your computer, Once you have it located, you attach it to your email just like you tried.........