How to predict character using knn algorithm

 Hi i have done sucessfully this code till feature extraction

I = imread('C:\Documents and Settings\vijaykumar\Desktop\today\z.bmp');
imshow(I)
Igray = rgb2gray(I);
imshow(Igray)
Ibw = im2bw(Igray,graythresh(Igray));
imshow(Ibw)
Iedge = edge(uint8(Ibw));
imshow(Iedge)
se = strel('square',2);
Iedge2 = imdilate(Iedge, se);
imshow(Iedge2);
Ifill= imfill(Iedge2,'holes');
imshow(Ifill)
[Ilabel num] = bwlabel(Ifill);
disp(num);
Iprops = regionprops(Ilabel);
Ibox = [Iprops.BoundingBox];
Ibox = reshape(Ibox,[4 50]);
imshow(I)
hold on;
for cnt = 1:50
rectangle('position',Ibox(:,cnt),'edgecolor','r');
end

But i my aim is to implement hand written character recognition using knn I mean i want to Predict the character how it is possible using knn algorithm i have seen this KNNCLASSIFY But iam unable to understand suggest me any code how we can do that thanks in advance.