1.) Once you launch the softphone a new window will pop-up with your "SIP Accounts" Click on the "Add.." button.

Enter the following SIP configurations:

Account tab:

Display name
Username
Password
Authorization user name
Domain
Register with domain and receive incoming calls
Send Outbound via

Your name and last name
Nymgo username*
Nymgo password*
Nymgo username*
ata.nymgo.com
CHECK
Domain

* Your existing Nymgo username and password

Topology Tab:

IP Address:
    Discover Global Address radio button: "Checked"

Stun Server:
    Use specified Server: stun.nymgo.com:80

2.) Click on the "OK" button

3.) Click the "Close" button in the new window. Now you are ready to make calls using Nymgo.