save characters to a file

Hi,

On a Form I have got 3 listboxes.
With a:
open("test.txt") For Output As #1
command a text files is read.

In the text file are 3 colloms:

test1 100 10
test2 150 50
test3 50 150
test4 10 100

These collombs are placed in the list boxes.
In the form I can only modify listbox3. (10-100)

Let's say I change in listbox3 the lines to,for example:

100
150
50
10

By clicking on a button (command1), I want to save the file.
It has to look then like:

test1 100 100
test2 150 150
test3 50 50
test4 10 10

But I want to specify only the insertionpoint of the characters or line numbers.
Without overwriting the already existing characters of the first and second colloms
(test1 100)(in this example line 1).
The first and second colloms may not be changed at all.

Does anyone have an idea?
If it's possible, please send some example-code.


Thanx,
Maarten