Under Invoice it says pending non-posting

It's nice to see you here today, @prefmaint. 

The Pending Non-Posting status on your invoice means that it isn't final yet. This also doesn't affect your customer balance. 

To help remove the pending status, I'd suggest marking the invoice as final. This way, the transaction's amount will be posted on your customer's account. Then, you'll be able to send it to your customer. Just open the invoice, and click the Mark As Final button at the top of the transaction screen. See the screenshot below for your visual reference. 

Once your customer pays the invoice, use the Receive Payment feature to enter the payment in the program. Just go to Customers from the top menu. Then, select Receive Payments as seen in the screenshot below. To proceed with the steps, go through this article: Record An Invoice Payment. 

Just click the Reply button below if you have other concerns. Have a great rest of your day, @prefmaint.