Dear Aleš_1, you are a new member of these forums, so we will give you a bit of slack. I have over 15 years Linux experience, but just saying "WiFi" in a post is not particularly useful to help you. Many Linux distributions (you don't mention which yours is) don't directly support proprietary WiFi drivers and firmware. They are available, and I have NEVER been unable to get my Linux WiFi working (I only use Linux on my systems). So, please post this information:
Distribution and version of Linux you are trying to use.
Output from lspci and lsusb so we can find out which chip set your system is using.
After that, we can make appropriate recommendations. Thanks.
@Dani - if her network tools show an SSID, then the driver and firmware are working. I don't think that is her problem, at least in my experience. It probably doesn't show any connection at all, but obviously we need more information.
P.S. I also post help on the LinuxForums.org web site, under the same pseudonym of Rubberman.