By the way, i have to develop web application using .Net platform with C# language. I need to connect to some service that provide map data, from my aspx page.
Is there any simple example of how to make a basic connection and just display the data?
Making a connection with asp is something you have to ask in an asp programming forum. You need a http component and then use one of the urls which are described in the osm api. See http://wiki.openstreetmap.org/wiki/API_v0.6.
You will receive data in xml format.
You did not tell what you want to do with the data … display ? You want to see the xml text?