Android setup files have the extension ".apk" which is a variation of the more common ".jar" format. You can see what is inside one by unpacking it with winzip,winrar or 7zip.
Installing:
There are various ways of getting apk files onto your scroll for installation. You can download them into the nand memory using the browser, copy them onto the scrolls memory card using a card reader, or even copy them onto your scroll direct from your pc using the usb connection.Note that if you download an apk file with the inbuilt browser it will be stored in /nand/download by default.
Once you have the apk file on your scroll, open the app drawer and click on "app installer". This will open and scan your scroll for apk files. Note that it will scan only the internal nand memory by default. If you have put the apk file on a memory card inserted in the scroll you will need to change the scan directory. To do so press the menu hard button, click "scan folder" and change the directory to /sdcard (highlight the orange box and the keyboard will appear - delete what is there and type in the directory) Note that it will automatically scan sub folders.
Once you have found the apk file, simply click on it to install.
Uninstalling:
Press the menu hard button, then "settings", "manage applications" Choose the app to uninstall. Click "force stop" in case it is running, then "clear cache" then "uninstall".