Select first row by default in datagrid

Hi all,

The situation is such that I have a somehow made a scrollable datagrid using a classic datagrid inside a DIV. Then I made it possible to select an item in the grid and change the selected item index of the datagrid each time the user presses on the arrow up and down keys. But the first time that the grid/page is loaded, no item is selected and when the user presses on the arrow keys the DIV is scrolled instead of the elements inside the datagrid. So what I would need is to set focus on the datagrid on page load, I tried this but then the first item is selected only when the user presses on the Enter button. So my problem is: how can the first element in a datagrid be selected by default on page load knowing that each arrow key pressed would changed the selected item index.

All help appreciated,

thanx....