If you have a D90 this is covered in the manual. Something I need to dive into a bit deeper myself. Sorry I can't be of any assistance in actually providing an answer. But I do know it is in the manual of most cameras you buy.
Also I think the OP's attitude comes from being essentially attacked. That was uncalled for which in turn caused him to have a bit more attitude with a response. Neither individual was right in this situation. All too often I find it's hard for noobs to really feel comfortable asking questions, for fear of essentially being called lazy or made to feel dumb. There's never a stupid question. Chances are I will come here to seek out answers before plugging it into google. Why? Because this is a photography forum. This is a beginners category, while this question may get asked a million times why not just answer, post a link to this very question being asked, or better yet just don't say anything at all. With no responses the poster is then made to look esle where for answers. I just don't find "google it" to be the least bit helpful. So if I now 'search' spot metering on this forum just how many threads will I actually find to be useful? My guess is anyone who has asked this question gets anything but the answer their looking for. Forums are here for a reason, if no one had any questions with regards to photography the beginners forum would never really exist.
Please be mindful that we were all 'noobs' at one point or another. We all have our own ways of seeking out answers for our questions. I just felt overall this could have been handled better. I hope it didn't discourage the OP from participating in the forum. I hope they continue to ask the 'basic' questions be it through google or reading their manual or possibly on here. That is the only way we learn. I just think a bit more understanding could go a long way with some of these sarcastic and rather rude replys to this question.