Go to Afternic.com and create an account. If you already have an account with GoDaddy, you can use that to log-in.
Once you're logged in, click "Portfolio" on the left hand side, and click "Add domains."
From here, you'll add your domains, you'll choose prices, and then you'll opt-in to their reseller network.
Here's for information about it.
The process is similar for Sedo and Dan.
If you decide to use Dan's landing pages, you'll want to create an account at Dan, add your domains to your portfolio, and then set Dan's nameservers for your domains. You can still have your names listed in Sedo and Afternic without using Sedo and Afternic's nameservers.
I haven't really gotten any traffic from Dan's marketplace, but they're my choice for in-bound leads, in other words, when people type my domain names into their browser.