Classification of images uisng SVM classifier

Can anyone help me in the code of image classification using SVM classifier.....

I have done image pre-processing, segmentation and feature extraction.... I even know that i have to form a matrix of these features extracted and input it to the SVM classifier....

However I am not able to understand how to input these features to SVM classifier...and how to use classify images using SVM...can anyone help me in this......