Uploadify simplifies uploading images allowing you to pick images through the computers native file picker interface and uploading multiple files at once. Flash is the technology used in Uploadify and unfortunately Flash has been known as a vector for many security issues. You need to enable Flash to enable Uploadify. You can either do this just while using Uploadify or you can enable it for specific URLs or domains (sites).
If flash is enabled, when you go to the Uploadify tab, the browse button will visible. If the button isn’t visible, then flash is not enabled.
Complete instructions can be found in this link, click to open Enabling Flash in Your Browser to use Uploadify