spanish

When I want to apologize for my poor English, I write "...and please forgive me if my English is too lame". (Have no idea if I say it in a correct way.) How to say something like this in Spanish (because I believe my Spanish is even lamer)? I don't mean exact translation, just something with the same meaning.

And the second question: when I come first time to some english forum or community I say "Hello, friends" or "Hi, guys". How should I say my hi's in Spanish? Any advice if I wanna go to the community of mexican indians (speaking spanish, thanks God, not only their native language)? Is it polite to call them "amigos" if I'm just some curious turista, not an indian at all?

Thank you in advance.