Hi! I'm italian so sorry for my BAD english..
This is my question: Can i make a city on gold,silver,iron and other resources....?
If i make a city on iron, for example, then can i use that resource?

excuse me if it's a stupid question..

Yes of course. Founding a city on a resource automatically develops that piece of land, to the extent possible given your level of research. Try it and you'll see what happens.

Thank you very much! I was confused because of improvements..
However I try it! ^_^

You can do that, but you will lose most of the bonuses (in terms of hammer/food/commerce) in doing so.

Be sure to take into account what dirtyparrot said. It'd be a shame to settle on gold or gems, because you'd lose the commerce they bring in. Same with iron, although sometimes if it's a critical need or if there are fears you could lose it culturally, I'll do it.

The only resources I usually will settle on are ivory and some of the calendar resources (because they're often clustered and not typically that much more valuable improved).