Converting data from a textbox to lower or upper case

Dim strCowBiscuit as String
'Let's say the textbox is txtCowBiscuit

strCowBiscuit = txtCowBiscuit.text.ToUpper

or

strCowBiscuit = txtCowBiscuit.Text.ToLower

This assignes a string variable (strCowBiscuit) to what's inside the textbox (txtCowBiscuit) and changes it to upper or lower case