You need to read the documentation. This is really a simple problem and your code is close.
v1 = randn(1, 255); % We need this in order to do the copy
graph1= zeros(1, 100); % Note this is not 1:100
i1=50;
i2=55;
graph1(i1:i2)=v1(240:245); % Your code had I, which you never describe.
