Supplemental to the above - on your computer, download
BlackBerry OTA Downloader. It's a single EXE file. When you run it, simply paste the URL to your JAD file into it and click the [Download] button, and it will download the JAD file and all the files needed for the program into a folder with the name of the program which you can then copy to an SD card, and use the Media application on your BlackBerry to explore, and then just click on the JAD file to install the app. Details
here.