Bbbnnsms
I assume by 'outgoing letter' you mean an email? If so, then a copy of the email can be found in the Sent folder, found below Inbox.
copy file filecopy
The most common tool used for copying files is Windows Explorer (similar to, but not to be confused with, Internet Explorer).
Normally folder refers to a container, which contains files, which are electronic documents. There can be some confusion, because: Often the word file is used to refer to a folder, but rarely is "folder" used to refer to a file.
BY create an uncompressed copy of a file I asume you mean make a copy of the compressed file and have the copy be uncompressed. all you need to do is unzip it.
backup
That would be a 'back-up' file - assuming you have one ! A back-up is a copy of something that you can go back to in case something has happened to the original.
In MS-DOS, "copy con" is a command used to create a new text file and enter text directly from the command prompt. On the other hand, "copy" is a command used to copy files from one location to another. The "con" in "copy con" stands for console, indicating that the text is being copied from the console input.
A file folder can hold paper documents. A folder is also the same terminology used in computer lingo and means the same, as a "folder" to save electronic documents and pictures.
A compressed folder can have many extensions. The usual windows extension is .zip. But .7z (for 7zip) and .rar can also be used.
backup file
copy and paste