If you have a file ready, you can import an existing Gliffy diagram that has been saved in .gon, .gliffy or .gxml format, or Visio diagrams that have been saved as .vdx files or .vsdx (Gliffy for JIRA v4.5 and above).
1. Go to More->Add Gliffy Diagram
2. Select Import a Diagram
3. Click “Choose File/Browse” to locate your file on your desktop. Double-click on your file to select it. You will then be launched into the Gliffy Editor.