Cod files are the actual app (like an exe). Jad is the installer (so to speak) for an ota install. Check the app to see if there is an alx version which will allow you to install the app to your phone using dm.
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Transfer the .jad file to your device memory or SD card. Then use BBFileScout (now know as FileScout) to locate and open the file. The browser will then "download" the app from where you stored it and install.