My first question would be....why are you creating a form that has a form action of mailto instead of a far better solution like a forms plugin, such as Contact Form 7 (many other options too)? Ultimately, you get a lot more options and flexibility with a plugin method.
The one big problem is that your email address is easily picked up by scripts that can take advantage of it and enter you in a world of spam and other abuses.
Although I don't have a setup tutorial for Longevity with regards to creating a Contact page, I do have one for my Aberration Lite theme if you are interested?
However, there are tutorials online for email forms that you can google, such as this one: