Converting long program to program with fminsearch

Hello, I have made a long program with random walk with identification criterium. Now i have to delete the random walk and use fminsearch instead of this random walk. My code:

 clear all
clc
load pomiary.mat  
X=[4 8 3 5 2 8 3 2 6 2] 
Y=[6 3 8 3 9 9 9 3 2 7]   
x_min=min(X);
x_max=max(X);
os_x=linspace(x_min,x_max,50);
a=rand;      
b=rand;     
c=rand;
Y_m=a*X.^2+b*X+c;  
E=(Y-Y_m);    
Q_0=(sum(E)).^2/length(X); 
Q_best=Q_0+10;
Qbest=[];      
A=[];      
B=[];      
C=[];
z=1;         
j=1;
for i=1:100
while Q_best >= Q_0
    if z>10000000
        a=A(end);
        b=B(end);
        c=C(end);
        break
    end
    a=a+randn/50;       
    b=b+randn/50;
    c=c+randn/50;
    Y_m=a*(X.^2)+b*X+c;
    E=(Y-Y_m).^2;
    Q_best=sum(E)/length(X);
    z=z+1;
end
    if Q_best<Q_0
    Q_0=Q_best;         

    Qbest(j)=Q_best;      
    A(j)=a;           
    B(j)=b;           
    C(j)=c;
    Z(j)=j-1;
    j=j+1;
    end
end
Q_best 
figure
os_y=a*(os_x.^2)+b*os_x+c;
plot(X,Y,'+r',os_x,os_y,'r')

I don't know how to start. I think its good choice to delete the part of the program from while loop to end of this loop and use fminsearch here somehow. It's good idea? How to make it?