This easiest way I've found to download a cartridge and use the whereyougo app on my Galaxy S3 is to download the following - Google Chrome Browser and Download All Files. Both apps are free and they help enormously. The android browser only downloads cartridges as "htm" for some reason, however google chrome will download the proper "gwc" file. Simply download the cartridge in Google Chrome, MOVE the cartridge to the "whereyougo" folder using Download All Files (if there is no whereyougo folder on your phone, simply create one). Now, when you open whereyougo and press start....voila!