These designs are part of the Partial to Parterre collection and are meant to be used as elegant backgrounds for social media stories and posts. The designs include transparent oval cutouts, making it easy to add them on top of your desired photo, and feature multiple colors, including blue and green.
 
Here are specific recommendations for using these templates on instagram:
 
For a full-screen, plain background: Save the background on your phone or computer, open Instagram stories, and add the background as your base layer. Finally, place your text, stickers, or photos on top! 
For a full-screen background with transparent cutouts: Save the background on your phone or computer, open Instagram stories, add the photo you want to be your background photo, click the sticker icon (the square smiley face on the right side), click the photos option, and finally add the full-screen background template with the transparent cutout on top! You may have to adjust your background photo slightly to make it fit correctly in the transparent cutout. 
For a small centerpiece overlay template: Save the background on your phone or computer, open Instagram stories (specifically, click the add icon, then scroll to story on the bottom), click layout and choose your layout option (like the 4-photo grid), add your background photos to the selected grid (by clicking the photo icon in the left corner),  click the sticker icon (the square smiley face on the right side), click the photos option, and finally add the small centerpiece overlay template on top!