This article explains how you can tag users in your Instagram post made on Gramto,
1. Click the Advanced Settings Option while creating your post.
2. Select the User Tag option.
3. Type in the username or name of the person you wish to tag
4. If you'd like to display the tagged user on a certain position on the picture. Simply click on the tag, then click on the position of your choice.
Setup every other aspect of your post, then publish.