Category - Subcategory in Asp.net Vb.net Datalist

I have database in MS SQL Server

Hi, i have two tables as;

First table name: Categories
Columns: cat_id, cat_name

Second Table Name: Subcategories
Columns: subcat_id, subcat_name, cat_id

cat_id in both tables has relationship.
In asp.net page i want to get these rows in datalist like

Category

 - Sub Category
 - Sub Category
 - Sub Category

Category

 - Sub Category
 - Sub Category
 - Sub Category

How do i do that in VB.NET please explain it ?