wifi internet connection

[bmw325]

hi am new here . i ahve trying to access the internet for a week now using my laptop. it is a centrino . so basically , the card is being able to detect the wireless network availbale but i cannot access them!!!!! and the wierd thing is that my friend who is sitting to me can access. ( but when he clicks on the show the available network , nothing showssss)

please any help is appreciated