.jar and .jad are OTA (over the air) files. They are designed to be downloaded and installed directly to the phone. Only .alx files can be downloaded to the computer and installed via the apps loader in Blackberry desktop manager.
If you have a data program, this can be done easily. If not, you should be able to use your wifi connection and the BlackBerry browser to download and install the programs. This is how I got my programs onto my phone in the first few months when I did not have a data program.