Public visitors access

I’ve just created a subwiki instance, and would like this instance to be mostly in public access for visitors. Wiki admins/redactors would identify to edit the wiki, but most of the visitors wouldn’t need to register or identify. There would be a direct access to a welcome root page, and the wiki tree.
Seems simple, and I’m quite sure xwiki can do that, but I actually miss the way to do. Any hint or doc reference? Thanks.

The answer is in wiki admin part, acces right, users (i kept trying with groups for a while)
and set uregistered users rights.