嵌套If語句的使用方法與普通的If語句類似，只是在If語句中再次嵌套了一個或多個If語句。

下面是VB.Net中嵌套If語句的基本語法：

If condition1 Then
   ' code block executed if condition1 is true
   
   If condition2 Then
      ' code block executed if both condition1 and condition2 are true
   Else
      ' code block executed if condition1 is true and condition2 is false
   End If
   
Else
   ' code block executed if condition1 is false
End If

以下是一個示例，演示了如何使用嵌套If語句來檢查兩個條件：

Dim num1 As Integer = 10
Dim num2 As Integer = 5

If num1 > num2 Then
   Console.WriteLine("num1 is greater than num2.")
   
   If num1 > 0 Then
      Console.WriteLine("num1 is positive.")
   Else
      Console.WriteLine("num1 is negative.")
   End If
   
Else
   Console.WriteLine("num1 is not greater than num2.")
End If

在上面的示例中，首先檢查了num1是否大于num2。如果是，則輸出"num1 is greater than num2.“，同時檢查num1是否大于0。如果num1大于0，則輸出"num1 is positive.”；否則輸出"num1 is negative.“。如果num1不大于num2，則輸出"num1 is not greater than num2.”。

注意：在嵌套If語句中可以使用任意數量的If語句，只要滿足編程需求。