In my opinion, i prefer to use Matlab. Because using weka you need to transform your data to arff format and I don't really like Weka. If you want to use Matlab this is how you can do it: http://www.mathworks.es/es/help/stats/kmeans.html
Hi Jabbar, I'm not sure if I understand your question correctly. I think you want to use k-means as a way to determine the class of your data, am I right? If so you can use weka and set as k the number of your classes. I found a document that can help you to do so in Weka: http://www.bvicam.ac.in/news/INDIACom%202010%20Proceedings/papers/Group3/INDIACom10_388_Paper.pdf