You say you're new to Ebay, but you've been an ebayer for over 5 years. So not sure what you mean by that...?
Everything you need to know about selling on Ebay, including the 21-day payment hold, which is applied to all new and infrequent sellers, is in the Seller Centre (link at foot of any page). There's even a whole section there especially for newbies.
If the transaction says the buyer has been paid but there's no sign of payment at all in your PayPal account, that means you included the wrong PayPal email address during the listing process, and the buyer's payment is floating around in the ether with nowhere to go. If this is the case, come back for further advice.
If the Ebay transaction indicates that payment has not been made at all, I'm not sure why you shipped the item, or where you shipped it too. Orders must be shipped to the delivery address on the PayPal payment confirmation email. You must not ship to the address on the Ebay order confirmation, as that is the buyer's Ebay-registered address, and not necessarily where the buyer wants it sent. The order confirmation email tells you that.
If the buyer never made the payment, all you can do is open an Unpaid Item case, and hope the buyer pays. If they don't, close it as 'unpaid' after 4 full days to get the selling fee credited back to your Ebay account.
@kotandmur
