The custom domain name feature allows you to setup your Weebly site with a domain name you've already registered through Yahoo / AT&T Small Business. The changes we request are simple, but it can be a rather frustrating task if you don't have any experience with editing your domain records. We recommend that you register your domain through Weebly if you are looking to buy a new domain.
To configure a domain from Yahoo with your site:
First, you'll want to change your site address in the Settings tab in the editor. Save your changes and copy the IP address you're shown. Log into your Yahoo account and then go to the Domain Control Panel for the domain you want to point to Weebly.
Select the Manage Advanced DNS Settings option from the next page.
By default, Yahoo has two A-Records and a CNAME record (that look like just like the ones shown below) that will need to be altered to point the domain to your site.
Edit each of the three records so that their destination is the IP address you got in the Settings tab.
Note that it can take Yahoo up to 24 hours to point a domain here when you make your changes (it usually only takes a couple of hours).