I was wondering if anyone could help me? I basically need a basic sequence diagram to satisfy the scenario listed below, but have never done one more before and don't know where to start. I really need it SAP so if anyone could help, I'd really really appreciate it.

Scenario:

A real-life example of a client-server relation could be the following: A user connecting to eBay at www.ebay.com - the Website provides a cluser of high-powered machines optimised to service requests from the Internet, i.e. servers. On the other side, the user connecting to eBay will be using a machine that is providing no services to anyone else on the Internet. This therefore can be termed a client