How do I add multiple photos at once?

MOBILE: 

iPhone: Go to the specific group album you want to add multiple photos to and in the center of the bottom of your screen tap the blue "Add New Photos" icon (the camera with the arrow pointing upwards). Tap "Choose Photos". Select as many photos as you want. When you are finished selecting all the photos you'd like to upload, tap on the blue "Upload <#> Photos" button at the bottom of the screen. 

Android: Go to the specific group album you want to add multiple photos to and in the upper right-hand corner tap on the "Add New Photos" icon. Select as many photos as you want. When you are finished selecting all the photos you'd like to upload, tap on the blue "Upload <#> Photos" button at the bottom of the screen. 

WEB: At the top of the specific group album in question click on the blue "+ Add Photos" button just below your cover banner, on the right-hand side. You can either click "Choose Photos" to select as many images from your computer as you want, or you can drag them straight from your desktop to the designated space.