Yes, the accounts you wish to post to must first exist in the books before you can post to them.
Create a General Ledger Report under NewViews > Report > Sub Reports. Create the General Ledger/Trial Balance Report and in the window below choose Account Setup. Insert your accounts specifying the appropriate account type (F3 to pick), account name, account description, normal balance and representation.
When the General Ledger accounts exist, complete your posting from your Opening Entries Journal. I suggest that you create an account called JOURNAL_BALANCE which is a General account type that exists on your General Sub Folder of NewViews > Account and use this account as your Debit account in your opening entries journal.
Remember to total the General Ledger accounts to your Income Statement and Balance sheet reports. These accounts would be type TOTAL.
See the NewVIews 2.08 Manual > Setting Up The Books for more information.