matrix inversion and how to set range

[coralline algae <corallina gmail com>]

I  am new to gnumeric.  I have a 3 x 3 matrix that I want to invert.  I
am using the  minverse function and after searching the mailing
list see that my problem is that I need to specify the range
to insert to.   My problem is that I dont know how to set range.

After typing in this 3x3 matrix
  
1,1,2;
2,1,2;
2,0,1

I select insert function from the menu bar and 
click on  array area then select the cells 
of the matrix.   The box fills with  Sheet1!:A5:C7 

If I click ok I can see the range is wrong but
how do I set the range.  I tried highlighting
a 3x3 blank area before the insert but that didnt
work.

Thanks