Navigate to your voice portal link and include /fop2/admin after the .com:
If you are prompted to login, enter your Voice portal credentials.
Click the Users tab on the left.
Depending on the actions you've taken prior to coming here, there are two paths you will want to take.
If a new user was created, but it's not showing up in fop2, navigate to Actions > Recreate Users at the top right and then Actions > Reload Panel. This will create any missing extensions and update the fop2 panel.
If you updated an extension's display name using this guide, you may want to reload fop2 to display the new name. You will only need to go to Actions > Reload Panel to update.