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you download backup1.zip in /uploads/ then in mysql table where you store the upload information you can store its name like /uploads/backup1.zip
then just link it in your pages for downloading.
there are different issues which you may be considering e.g how to hide the actual download link so that people cannot hotlink your files or get the uploads directory path.. you can do it with php easily then by composing the download link and using HEADER() to redirect to the file or some other similar trick.
the link would look something like
where 12345 is the id from the row in mysql
the script would get the path and all info about the file from the db by using the id passed in $_GET
then it puts together the headers and forces the download
For that you might use generate a timestamp based unique number for the user and store it in a download-queue table. email the link,as jatar_k told you. When the visitor visits the link, check if the unique number embedded in the link exisits, if it does then send the visitor to the download page and remove the unique number / download request number from the table.
if the number doesn't exist simply show the requist expires or wrong request number error.
You will face lots of problems if your base is not firm and you are completing tasks with quick helps.. so I will strongly suggest you firming your base by learning php properly.
this is how it works