Automatic installation
You can install Attach File Manager for Jira through the Universal Plugin Manager (UPM). For information on how to use UPM, take a look here.
Manual Installation
If you have the app file (a file with the extension .jar),
- Go to the Administration section of Jira and look for the Apps menu.
- Select Upload App and upload the JiraAttachFile-X.X.X.jar file (where X.X.X is the Attache File version).