Adding .jar files isn't so tough.
A .jar file is a Java midlet program that is used to play games and other applications. While some phones use other operating systems, many smartphones use Java-based operating systems and run applications, or apps, that are in the .jar file format. You can download .jar files from the Internet onto your phone using its native functions.
Instructions
1. Open a browser window on your computer and find the web page with the Java application you wish to add to your phone.
2. Download the application to your desk top.
3. Enter the URL "http://rumkin.com/tools/sprint/" into the address bar.
4. Enter your address information into the "Recipient" field of the "Games, Applications, and Java Midlets" section.
5. Click "Choose File" and then click the "Desktop" icon in the side bar of the window that pops up.
6. Select the .jar file that you downloaded earlier, and then click "Open."
7. Select the folder that you want to store the .jar file in. Download games to the "Games" folder, for example.
8. Click "Send Midlet."
9. Select the download URL from the text message that you receive on your cell phone.
10. Choose to download and install the application.
11. Run the application.
Tags: operating systems, then click, your phone