C# :: Increment Records By 1 And Update In Table?

This is my code as following

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;

[Code]....

I have driver table this is my fields as following
DriverID INT
DriverName nvarchar50
Nationality nvarchar50
Address nvarchar50
I have form driver have 4 texbox
textbox1 DriverID
textbox2 DriverName
textbox3 Nationality
textbox4 address
this table have two records

when i press buton next (NextBtn_Click)to go third record it not accept I need next button increase by 1 if record not exist and update this in table How i do this example if i have two records

1 aln american newyork
2 adam british british

when i press next button it ok work in records exist but when i press next button to third record it not accept why what i need is when press next after 2 it come 3 in text box driver id and update this number in table