I cannot see any proxy settings button in preferences section
To set a proxy server in Firefox 4 beta for Android:
Are you missing that "network.proxy.type" needs to be set to 1?
Also, if it's a SOCKS proxy, then the related options are in "network.proxy.socks*".
I was able to follow the above suggestions in this order:
I can connect via proxy with your advices but I cannot navigate becuase my proxy works with user and password. Do you know if there is any other param in wich enter them?
Thanks in advance,