What's the URL/control panel for my resold client to login?

Reseller Plan > New control panel
Your clients can login to the control panel at http://member.mysitepanel.net

How do I get my own URL?

You can simply setup a CNAME record for member.Yourdomain.com to point to member.mysitepanel.net and you'll be able to use http://member.yourdomain.com
1. Login to your hosting control panel-->DNS  from the top navigation, select the target domain and click "Manage" button beside it
2. Set the Cname record