D-Link ShareCenter DNS-340L User Manual page 215

Section 4 - Configuration
Under the Select Photo section, click the Browse button to search your
computer for photos.
If you wish to add more than one photo, repeat the process or hold the Shift key
to select a range of photos, or the Control button to select several individual
photos.
Click the Open button to add them to the Album.
D-Link ShareCenter DNS-340L User Manual 208