The MS Access databases should be uploaded to your "DB" folder.

The ASP.Net way of creating a connection to an MS Access file is:

Dim connStr As String, dbconn As OleDbConnection
Dim dbName as String="mydatabasename"
connStr = "PROVIDER=MICROSOFT.JET.OLEDB.4.0;DATA SOURCE=C:\domains\mydomainname.com\db\" & dbName & ".mdb"
dbconn = New OleDbConnection(connStr)

UPDATE:
You may want to download our sample code using .Net user impersonation to successfully amend an Access database using ASP.Net. The URL is http://ssl128bit.net/downloads/tools/testDB.zip

(View the readme.txt file within the ZIP archive for clear and simple instructions.)