Question about installing airport card?

Ok so I went to put the airport card into this computer, and I couldn't figure out if I am supposed to clip that metal part OVER the airport card, or lay it underneath. Was metal wirey thing meant to hold in the airport card? I did get it in there like that but it made the keyboard slightly bulgy because it sticks up a little. I also have another problem. The screw in the middle on the keyboard is completely stripped and I can't get it out again. Also is there a way to figure out if that mac recognized the airport card? I have AT&T Uverse and I cannot go online with it so far with the airport card. Our AT&T is not wireless though so that may be why. Is there something special I have to use/test this? I know Starbucks has wifi so maybe tomorrow I should just go there and try it?