Instagram allows you to take a photo or choose a photo to upload and share it with other social networking sites. You can send your photo as a private message to your followers and friends. Once you have take a photo or choose a photo, you can add any effects or filters to your photo. After adding effects or filters, a 'Share to' window opens up. Here tap 'Write a Caption' to add a caption and tap 'Ok' button and then tap 'Share' button to upload your photo.