1. You should upload both a JAD and JAR file, and begin downloading the JAD (the JAR will then download automatically). Some phones can download the JAR directly, but this is not strictly the correct process, and many phones will not allow it.
2. MIME types. HTTP servers associate a type with each file extension. To deploy a mobile Java application, the following types are needed.
It is also worth installing by cable or Bluetooth, just to check that the application will work on the phone at all.
.jad -> text/vnd.sun.j2me.app-descriptor
.jar -> application/java-archive