Hi charlo26 - what exactly is it that you're doing? For example, are you registering a domain name through Yahoo or are you trying to <a href='http://www.inmotionhosting.com/support/domain-names/dns-nameserver-changes'>update the domain's nameservers</a> and point them to InMotion Hosting?
An addon is simply another separate domain name you want to use on your account. So if your primary domain is abc123.com and you want to use xyz789.com as an addon domain, they both would operate as their own independent website.
A parked or redirect would point to another domain name and display the same site. Using the same domain names as above, if your primary domain is abc123.com and you use xyz789.com as a parked or redirect, whenever someone typed in xyz789.com they would see the same site as abc123.com.
So, to get to an addon domain, simply use that domain name (xyz789.com). For Yahoo, what they are asking sounds like it is a redirect of sorts, so you will give them whatever domain name you want to point to. If you want it to redirect to abc123.com then that will be in the place of the www.???????
Now I'm completely confused. My domain main domain with inhosting is:
www.charlottebell.com my sub domain is www.travisheightsart.com
so what do I type into to forward at yahoo? how will they no travisheightsart.com is under charlottebell.com?