This tutorial will explain how you can add funds to your PSN wallet by using the PlayStation App. It is important to note that you can only add funds by using a gift card for this method.
Once you have a gift card, you can take the following steps:
1. Open the PlayStation App.
2. Next, you need to tap the PlayStation Store icon.
3. You then need to tap the Menu option.
4. Afterwards, tap Redeem Code.
5. You then need to input the voucher code on your gift card and then tap continue to redeem.