What you're asking for requires preparation. If you are a beginning coder, learn the file system object(s). You'll need to create directories for each user. This is probably best done when you create the user - i.e. create the user and use an autonumber. In SQL something like:
User_Index int identity(1,1) NOT NULL CONSTRAINT PK_user_name1 PRIMARY KEY
You'll then be guranteed that each user will be unique.
Use the filesystemobject to create the directory when they register, then like posted above, use that column to determine where they go. You may wish to have a default set of files to write to their directory. I'd create that set and then read it in, replace whatever you need then write it to their directory.
What you've described is more than just a few lines of code. As posted above, response.redirect will do the redirection, and that's pretty much dirt simple. Here's a simple script that I use to write files (not directories):
<%
SUB fileWriter(PathName, FileName, FileString)
dim fsoMyFile
dim myfile
SET fsoMyFile = CreateObject("Scripting.FileSystemObject")
SaveToLocation = PathName & FileName
SET myfile = fsoMyFile.CreateTextFile(SaveToLocation, 1, 0)
myfile.write FileString
myfile.close
set fsoMyFile = nothing
set myfile = nothing
END SUB
%>
The function accepts three things: the path (your directory), the new file name, and a string for the actual file you want to write.
I'll leave it up to you to figure out how to create directories. (It isn't that much different.)
HOWEVER - each page in the user's directory should check to find out if that is the right user, and if not, response.redirect ("../index.asp") or whatever. You'll probably need to use cookies there as well.
As for the Access database, that is the least of your worries. You've got a lot to figure out for what you've asked.