NewtonForward[n_,x0_,h_,f_,x_]:=(
poly:=0;

fi[i_]:=f[x0+i*h];

deltaf0[k_]:=(
deltakf0:=0;

Do[
deltakf0+=((-1)^(k-j))*Binomial[k,j]*fi[j];
,{j,0,k}
];
deltakf0
);

t:=(x-x0)/h;

Do[
poly+=deltaf0[i]*Binomial[t,i]
,{i,0,n}
];

poly
);

funct[x_]:=3*x^2+5x-6

NewtonForward[1,0,1,funct,x]