How to use k means to make 30 clusters with circle around each cluster and mark the center?

 If I have a code which draws a circle and generates 100 random points inside it. I want to use k means to cluster these 100 points into 30 clusters with a circle around each cluster to differentiate between the clusters and i want to mark the center if each cluster.this is the code of the circle and the 100 random points inside it . Any help please ?

%// Set parameters

R =250;  %// radius
C = [0 0]; %// center [x y]
N = 100;    %// number of points inside circle

%// generate circle boundary
t = linspace(0, 2*pi,100);
x = R*cos(t) + C(1);
y = R*sin(t) + C(2);

%// generate random points inside it

th = 2*pi*rand(N,1);
r  = R*randnlimit(0, 1, 0.5, 1, [N 1]);

xR = r.*cos(th) + C(1);
yR = r.*sin(th) + C(2);

%// Plot everything
figure(1), clf, hold on
% subplot(1,N0,1);
plot(x,y,'b');
hold on
text(0,0,'C')
plot(xR,yR,'p')
axis equal
zR=cell(N,1);
for i=1:N
    zR{i,1}= [xR(i) yR(i)];
end

m=cell2mat(zR);