I think he just wants to know how to get the Row Index of the SelectedRows....

If it is that it depends, If you are trying to  get it in a javascript function I think it's something like this

var grid = igtbl_getGridById(gridId) 

for(var rowId in grid.SelectedRows)
{
	var row=igtbl_getRowById(rowId);
	alert(row.getIndex());

} 

If it is server side it's a little more trick....cause it depends on where are you trying to pick this index...

try....UltraWebGrid.SelectedRows[0].Index;