Forms :: Move Between Datagridview Rows Using Up And Down

i have vb.net form contains one datagridview with data from database

my datagridview load data at the time of load event of form

i have one textbox1 in my form

my focus is in textbox1 t the time of load form

i need to move up and down through my grid when i press up or down arrow accordingly

currently i should click in any row then only i can move

how i can move between rows using up and down arrow by keeping my focus in textbox1
what i need to write in keydown or keypress ??

i need always focus in textbox, moving through grid up and down using arrow key regards