>I want to know how long he/she used the Internet Explorer to surf the Web. Can I do this using VFP?

If your users access the internet through a proxy server, you can log every hit they make and tie it back to computer name or possibly user login name.

For MS Proxy Server, there are server options for turning logging on or off. The logs are kept as comma-delimited text, so you can APPEND them into a dbf with APPEND FROM filename TYPE DELIMITED and then create a program to analyze them.