OK, what is the format of your file? CSV, fixed width? In this example, I'm going to assume it's going to be fixed width with CR/CRLF characters at the end of each line.
Function read_a_file(strFileName as String) as Boolean
Dim File_Number as Integer
Dim a_line_of_data as String
File_Number = FreeFile() 'The FreeFile command searches for the next available file
'number. VB uses the file number as a handle for any further
'access to or from the file.
'This will open the file quoted in the function parameters
'for Input Access
Open strFileName For Input Access Read Shared As #File_Number
Do 'Start a loop
'Fetch a line of data from the open file and put the contents
'into the variable 'a_line_of_data'
Line Input #File_Number, a_line_of_data
<perform your ifs thens and buts here>
While Not EOF(File_Number) 'Continue the loop until you reach the end of
'the file.
Close File_number 'Close the file
read_a_file = True 'Set the return value of the function
End Function
The example above doesn't do much, just reads and processes the contents of a file. There are other methods of reading data:
Get, Read, Input
Which depend on the type of data you want to read.
The output of data to a file is pretty much the same
Open strFilename For Output Access Write Shared As #File_Number 'To open a file
Then either use
Print #filenumber, [outputlist]
or
Write #filenumber, [outputlist]
Depending on the format of your data (use print for fixed-length, or Write for CSV
This should start you off - Excell has all this code supported in its help-files, so look up the Open statement, Input, Print #, Read, Write, Get, Put etc (In case your firm are too tight to buy the MSDN stuff - it's exactly the same thing)
Does this help?