Customer to Enter Shipping Amount

I'm trying to set up the shipping system in the Checkout, so that local customers can select from three flat rate options $2 $5 or $10, and international customers can enter the amount (as per the amount in the item description) in an empty field.

I've read about copying and renaming the flat.php file, so I could have flat1.php, flat2.php, unfortunately I seem to get stuck, when I click on copy file in my control panel, it asks me where I want to save the file, and then won't let me save it.

A request total option in checkout for customers who are unsure of the total would also be really useful.

As to the first part, if someone can suggest how I can complete the copy part of the process, I should be able to do the rest, changing all the flat to flat1, FLAT to FLAT1, and the same in the associated languages/english/modules/shipping/flat.php files.

Yesterday I didn't know what PHP was, so a simple explanation might be better.

Thanks

Well, I worked out how to create a new file, copy the script from the old file, rename all the flat to flat1 etc, but kept getting warning messages when I checked it in the ZC admin. There was a new flat1 module there to be installed, but I wasn't game with all the error in line 174 messages everywhere.
Can anyone tell me what my error in line 174 was?

Despite being reasonably adequate at following instructions, I continue to get warning and error messages in admin after I create new flat.php files for the shipping module.
Who else wishes they had actually just paid for a program that works?

Usually this is due to typos of mismatched case on the global replaces of flat with flatuk or FLATUK ...

Or perhaps you included an underscore such as flat_uk which would run into a conflict with flat ...

The modules need to "own" their own variables and filenames exclusively ...

These conflicts can show up in the catalog or the admin ...

NOTE: there are also 109 lines to flat.php ... :cry: