Many giveaway-contests require to repost photo in Instagram as one of conditions. It means that the photo posted by the contest organizer should be copied to participant's Instagram profile. Sometimes the users may be asked to copy a photo with description.
How to repost a photo in Instagram? There are several ways to make it.
Make a screenshot and post it
You should just open the necessary photo in Instagram on the phone, make a screenshot (make a photo of what your phone screen is showing) and load a photo back to Instagram after finding it in your photo gallery.
Using repost app
There are special apps allowing to make reposts with photo description. You should just register in the app, find the necessary photo and press "Repost" button. The photo will be opened in Instagram where you can edit its description, add any necessary filter and repost it.
Here are some free repost/apps in Instagram
Choose any appropriate for your phone:
Instarepost - Repost for Instagram download from Google Play: https://play.google.com/store/apps/details?id=com.repost
Repost for Instagram for Iphone download from Apple Store: https://itunes.apple.com/ru/app/repost-for-instagram/id570315854?mt=8
Repost for Instagram for Android download from Google Play: https://play.google.com/store/apps/details?id=com.redcactus.repost&hl=ru
InstaRepost for Iphone download from Apple Store: https://itunes.apple.com/ru/app/id800776936?mt=8