You must be talking about the web page where the OS file is located. Just figure out the download link and download. Download to where ever on your computer you typically download installers, then run it. It will install to your computer. Then continue with the instructions here on the forum for upgrading. The OS from any carrier, provided it is for your model, will work.
EDIT: You have 8310, right? Select 8310 from the dropdown, then click the button. Enviar means send, or something like that. The directions that fill in below after that are in english. Be experimental here. One step at a time.
EDIT: If you want to compare to the AT&T page, https://www.blackberry.com/Downloads...E4F82F9F00E7D4