The custom URL is just a "version" of your regular MerchantCircle URL (the link to your MerchantCircle listing page).
When you select a custom URL, you are not really changing the actual URL (link) to your MerchantCircle page, you are just creating another "version" of the link so its shorter and prettier. In a sense, the custom URL its just a URL shorten-er.
Click here to select your custom URL.
The first part of the URL (http://member.merchantcircle.com/) is filled out for you--just enter your business name or a version of your business name.
The Website URL
This is just a link to your external website, if you have one. Enter your website URL (link) and click "Save." The link(s) will show up on your MerchantCircle listing, under your Business Information.