Click on the Edit DNS link under the My Domain Names section.
Click the Edit Advanced DNS Records link next to the domain you want to use with Unbounce. This will open the DNS Manager Settings page.
Scroll down to the section Host Aliases: CNAME Records, click the Edit CNAME Records button.
In the 'Alias' field, type the name of your chosen subdomain. For example, if you picked promos.mydomain.com as your custom domain, enter promos here. Or, if you're using a root domain such as www.mydomain.com then you'll want to enter www here.
Select the Other Host radio box and type unbouncepages.com in the other host field.
Click Continue. This will bring you to a confirmation screen. (If you see the error "An A Record Already Exists for the Entered Alias" at this point, see below for instructions on deleting the conflicting A Record)
Confirm your settings and Click Save Changes
How to delete an existing A Record in your Network Solutions Account:
Follow Steps 1-3 above to access the DNS Manager Settings page.
Scroll down to the section IP Addresses (A Records) and click Edit A Records
Select the Deletecheck box next to record you want to delete. For example, if you are trying to create a CNAME record for the domain www.yourdomain.com, you will need to delete the A Record for the host www.
Click Continue. This will bring you to a confirmation screen.
Review the list of requested changes and click Continue.
You can then return to Step 4 above to finish creating your CNAME Record