Link to database cannot be established.

[Querbeet]

Hey
I have got a problem with the starting of the Webshop.
After i installed it successfully (got the email from the Webshop), i cannot open it.
Errormessage: Link to database cannot be established.
I tried to open de Webshop via www.(Webspace).ch/prestashop
This actually IS the correct folder, so i am quite wondering, what mistake i made.
The Version i Use is 1.2.4.
so, i really could need some Help

Thanks