When I asked about installing a Zip file and getting Message:Error: "No additional applications designed for your device were found",people assume that some of us "newbies" all ready have the Handheld Software istalled in our computers; I didn't. Did not even know I had to, since I was able to sink my Device with my Laptop via Desktop Manager. eg: contacts, tasks, etc.
Also backup my device.
After a little digging, I learned that we need the Handheld Software installed in the computer in order to install third party software. Once you install this software to your PC desktop, run it and follow instructions and it will install in your PC. Then connect your device to your PC and open your BB Desktop Manager and it will prompt you to upgrade. ( make sure that the zip file has already been extrated when you connect your device and start the BB Desktop Manager). You should find the zip file that you want to install in the window with some other applications that you allready have. Check the ones you want to keep and click next.
Make certain you download the Handheld Software for your provider and version in your device: options>about....I felt Great
getting this to work.
You can find the Handheld Software here: BlackBerry - BlackBerry Desktop and Device Software Download Sites
Scroll to your country and provider, then your device, then download.