Hello, I'm new in alfresco. I'm using Labs to develop a website where all the contents can bee seen by anybody, without enter the login and password. and the contents could be edited by the collaborators.
What sort of content? What sort of things do you want to use Alfresco for?
Your external web site application could use a proxy account or guest access to access data in Alfresco. Your collaboraors could use WCM to author and publish their content.
You can store all the public contents inside the space Guest Home and then you can implement your own WebScripts that allow guest users to get contents. The WebScript can execute queries or allow a navigation in the repo.