You need to fill the AutoCompleteSource of the textbox with the names of the customers. This can be done by a for loop.
Set the AutoCompleteSource property of the textbox to CustomSource and the AutoCompleteMode property to Suggest.
Then write this in the Load Event of the form.
For i As Integer = 0 to (YourDataSet.Tables("Table").Rows.Count-1)
You can experiment with the AutoCompleteModes to see which one mostly suits you're requirements.