Hello
Have you checked for typing errors in your connection string? The database connection string must be the same as the connecting database for your site, located on your server.
Have you requested asp.net 2 permissions from your hosting provider?
Have you read the DNN documentation for installation?
As you are new to DNN, I suggest you search for DNN installation tutorials, you will find several.
Try this site: www.dnncreative.com they have very good tutorials especially for people new to DNN. The instructions and narration of the tutorials are in English, however many of the tutorials are in video format, which you might find a little easier to follow especially as English is not your first language.
You might find this tutorial useful: How to Install DotNetNuke 4.3.x
http://www.dnncreative.com/tabid/289/Default.aspx
Or this: DotNetNuke 3.0: Installation & Configuration (Although this tutorial is for DNN 3.0 it is in video format. Dnn 3.0 uses a slightly different configuration file requiring only 1 database connection string, but many of the basic principles are the same.)
http://www.traincert.net/
Good luck
Lynn