[2.0] DLL Import

[Rattlerr]

I need to import a DLL using the Class.cs...this is what i have but its not correct..

static [System.Runtime.InteropServices.DllImport("dll file name")]

The Other issue i'm having is i used the Covert Tool in Visual Studio to upgrade a VB6 project to VB.NET,the Problem i having is with the F = FreeFile,
F = Split(LTD, ":")....

Here is the VB6 Code:

Dim LTD As String, F As Variant, x As Integer
 
F = FreeFile
    With CommonDialog1
        .FileName = ""
        .DialogTitle = "Load bots List"
        .Filter = "All Supported Types|*.txt"
        .ShowOpen
        If .FileName = "" Then Exit Sub
        Open .FileName For Input As #F
            While Not EOF(1)
            Input #1, LTD
            F = Split(LTD, ":")
            If x < 1000 Then
            Set Item = ListView1.ListItems.Add(, , , , 2)
            Item.SubItems(1) = F(0)
            Item.SubItems(2) = F(1)

Now when i used the Convert tool in VS 2005 to VB.NET the F = FreeFile was changed too:

F = FileSystem.FreeFile

I know the FileSystem is refering to the VB FileSystem used in Visual Basic .NET..I need to get that Over into C# along with the F = Split(LTD, ":"),
everything else i have already Reworked into C#..