In your ./includes/config.php find the line for "$config['Database']['technicalemail']" and enter the email address you wish to use. I wouldn't recommend putting your personal address. Instead create an address on your domain for forum errors (ie.
forumerrors@yourdomain.com) and put that in. You can always have those emails forward to your actual address if you want to make sure you see them, and that way if it does get spammed you simply change it.