It seems that I sucessfully installed ndiswrapper. The computer says that I am connected to my network at home (I was also able to pick up the signal of an unsecure network). However, when
I open the browser it says: "server not found". Could someone
tell me how i can find out if I am really connected to the network or why the browser is not working?
(I also used the command "iwlist wlan0 scan" to find
out if the network was being picked up, and from
the output of this command it is. So, what is wrong
with the browser?)

THANKS.
Maria

First thing is to check if you have DNSes set up correctly. Simply look into /etc/resolv.conf and check if you have lines like
nameserver <some_ip_address>
Do it when you're connected, with DHCP enabled that file is populated when connecting.

I fixed the problem. I just had to delete another network entry
(an ethernet adapter) that was not operational, since it was not
conncted to anything, but even though it was causing a problem.
When I left only the wireless entry everything worked fine.
(Thanks, Mara, for your suggestion).
Maria