simulation study

so i have to write a short programe for a simulation study, so far i have written

program define mysim

1. drop _all
2. set obs 19
3. gen b =inlist (0, 0.1,0.4)
4. more
5. gen u = rnomal(0,1)

Now the part I am stuck on is how to put into the simulation x = i
The question is yi = Bi + ui , so that xi = i and ui is N(0.1) for i = 1.....n
when B = {0, 0.1, 0.4}