Copy the Pic-a-Pix Deluxe NSP into that folder.
Navigate to File Browser > sdmc:/ and select your NSP to install.
If you don't want to remove your SD card, you can use a USB cable and NS-USBloader.
Navigate to File Browser > sdmc:/ and select your NSP to install. Pic-a-Pix Deluxe Switch NSP Free Download
If you don't want to remove your SD card, you can use a USB cable and NS-USBloader. Copy the Pic-a-Pix Deluxe NSP into that folder