How do you do arrays

[Thomas Bunce]

I am new at Pyton and I am learning from book not classes
so please forgive my being slow

The below does not work I get an Error of  File 
"Matrix[index] = k
NameError: name 'iMatrix' is not defined"

while  index < majorlop1:
   index = index + 1
   k = random.choice(listvalues) + 1
   iMatrix[index] = k

The book statement of 
 array(typecode, initializer) does not make sence
to me how it henerates ore relaes to the org name 
for the array.

Thank You
     Tom