eigenfaces : how to compute weights and how to classify new image

hello i want to classify images use eigen faces i transposed the images of train set to eiganface but now i have issue of weights computation and classifiying new image

%%----------------------- % here the issue i am not sure % 1 computing the weights Image = sum(weights* eigenface) ? % 2 new image classification process ?**

//=================

% i have M=4 images N*N   N=50
 [ st.data{1}  st.data{2}    ; st.data{3}     st.data{4} ];
% average image
for k=1:M
    st.data{k} = im2single(st.data{k});
    avImg   =avImg  + (1/M)*st.data{k};
end

    %%normalize (remove mean)
    for k=1:M
        st.dataAvg{k}  = st.data{k} -avImg;
    end
    %%generate A = [ img1(:)  img2(:) ...  imgM(:) ];
    A = zeros(N*N,M);% (N*N)*M   2500*4
    for k=1:M
        A(:,k) = st.dataAvg{k}(:);
    end
    % covariance matrix small dimension (transposed)
    C = A'*A;

%%eigen vectros  in small dimension
[   Veigvec,Deigval ]  = eig(C);% v 4*4 e 4*4 only diagonal 4 eigen values
% eigan face in large dimension  A*veigvec is eigen vector of Clarge
Vlarge = A*Veigvec;% 2500*4*4*4  =2500 *4
% reshape to eigen face
eigenfaces=[];
for k=1:M
    c  = Vlarge(:,k);
    eigenfaces{k} = reshape(c,N,N);
end
x=diag(Deigval);
[xc,xci]=sort(x,'descend');% largest eigenval

* **%%-----------------------
%  here the issue i am not sure 
% 1 computing the weights Image  = sum(weights* eigenface)  ?
% 2 new image classification process ?** *
%%weights
for mi=1:M  % image number
  for k=1:2   % eigen face for coeff number
    wi(mi,k) =   sum(A(:,mi).* eigenfaces{xci(k)}(:)) ;
  end
end

%%classify new img  mic
testFaceMic = imread('C:\Users\michaels.DSI\Desktop\faces\class\mic3.jpg','jpg');
testFaceMic  =rgb2gray(testFaceMic);
testFaceMic = imresize(testFaceMic,[N N]);
testFaceMic   =  im2single(testFaceMic);

Aface = testFaceMic(:)-avImg(:);
w1face  =  sum(Aface.* eigenfaces{xci(1)}(:)) ;
w2face  =  sum(Aface.* eigenfaces{xci(2)}(:)) ;