Format dates in gridview through code behind in VB

in my asp.net web i am binding data to gridview by code behind how can i format the date as 01/01/14. in my old pages i was using sql data source and i manually give date formating like below
DataFormatString="{0:dd/MM/yy}"    for 01/01/14
and
DataFormatString={0:f0}     for   number

how can i format these in code behind i am using VB as code