Open Instagram and swipe right to open the Story camera
Tap the gallery icon to choose a photo
Select the first photo you want to add
Tap the sticker icon at the top
Tap the photo sticker or gallery sticker
Choose another photo from your gallery
Repeat the photo sticker step to add more photos
Resize and move each photo on the Story canvas
Tap Your Story to post it
Use the Layout option in Story mode to place multiple photos in one Story frame
Use the Select Multiple option in the gallery if available to upload several photos at once
Create a collage in another app, then upload the finished image to your Story