Add Extra Fields In Your Pop-Up Author: Mayank Agarwal | Read more posts by this author. A Quick Guide To Add Extra Fields In Your Pop-Up In SendX. SendX makes adding extra fields in your pop-up a breeze. Read this short guide to find out how. Create a New Pop-Up or Edit an already existing one depending on which pop-up you want to add extra fields to. Go to the Content tab. Scroll down till you see the Fields area. Click on Add Field. Choose which field you want to add. Click Submit when you're done. And that's it! With just a few clicks you can start capturing more information in your pop-ups!