Treeview from 2 column list

Question

Hi,

I am pretty new to vb.net
I created a list with the following structure
category     parentcategory
Microsoft
Word          Microsoft
Save          Word

in order to create a treeview such as this
Microsoft
     Word
          save

I can't get it to add the 3rd level
Is there anyone ther who has an idea for creating treeview from a 2 column list ???
Thanks in advance