This is just example, how to read text file in Visual Basic for Applications (for example, in Excel macro).
It’s just a stub: there is no error processing here, the source file is really text file, no problems with permissions etc.
txtFile = Application.GetOpenFilename("Text Files (*.txt), *.txt")
If txtFile = False Then
MsgBox "No file to process"
Open txtFile For Input As #1
Input #1, myString