>how can u use MS VFP db at the backend and a web based application?is there any requirements?is there also codes to enter?pls help me

It’s the same as anything else. OleDb or ODBC. If you are using something like WebConnect it is all native and you don't need to do anything special. There may be some additional network access rights that need to be set if the data is on another server.
What language do you want to access VFP data from?