Trying to post multiple photos to Instagram with iPhone 6s.

I know I need to use my phone, not my computer. I have emailed the pictures from my computer to myself and opened them on my iPhone 6s in email. I was able to transfer the photos from email to Google Drive, but not to my Photos folder, or app, or whatever it's called. I think I can figure out how to post multiple pictures in one posting into Instagram when the pictures are in the Photos folder. But I can't figure out how to post multiple photos in one posting in Instagram when the photos are in Drive. I have been stuck for a week of trying. Thanks.