When you are making Instagram photos of your friends, you can also tag them in the photo. Here is how to do that.
- Access your instagram and tap the shutter button in the middle to take a photo.
- Edit your photo with various filters and Instagram photo editing tools. 
- Tap “Next” in the top-right corner.
Tap “Tag People”
- On the “Share to” page find the “Tag People” button and tap it.
- Tap the photo in certain area to tag people. (Usually it is where the people you want to tag appear on the photo.)
- Insert the name of your friend in the searching field. It will suggest someone from your followers according to the name you have typed in. 
- Select the one you want to tag and then tap “DONE” in the top-right corner. 
After you tap “DONE” you will be directed back to the “Share to” page.
- Write a caption for the photo on which you have just tagged your friends. (Optional)
- Tap “Share” button in the bottom to publish your photo.